Including header with overloaded std::ostream& operator<<(std::ostream&, typename T) causes build failure on gcc 10.2

**Describe the bug**

Build fails:
```
In file included from /home/john/googletest/googletest/include/gtest/gtest.h:58,
from /home/john/gnucash-git/libgnucash/engine/test/gtest-gnc-rational.cpp:24:
/usr/include/c++/10.2.0/ostream:773:5: note: candidate: ‘template typename std::enable_if >, std::__is_convertible_to_basic_ostream<_Ostream>, std::__is_insertable::__ostream_type, const _Tp&, void> >::value, typename std::__is_convertible_to_basic_ostream<_Tp>::__ostream_type>::type std::operator<<(_Ostream&&, const _Tp&)’
773 | operator<<(_Ostream&& __os, const _Tp& __x)
| ^~~~~~~~
/usr/include/c++/10.2.0/ostream:773:5: note: template argument deduction/substitution failed:
/usr/include/c++/10.2.0/ostream: In substitution of ‘template typename std::enable_if >, std::__is_convertible_to_basic_ostream<_Ostream>, std::__is_insertable::__ostream_type, const _Tp&, void> >::value, typename std::__is_convertible_to_basic_ostream<_Tp>::__ostream_type>::type std::operator<<(_Ostream&&, const _Tp&) [with _Ostream = std::basic_ostream&; _Tp = std::type_index]’:
/home/john/googletest/googletest/include/gtest/gtest-printers.h:216:33: required from ‘void testing::internal::PrintWithFallback(const T&, std::ostream*) [with T = std::type_index; std::ostream = std::basic_ostream]’
/home/john/googletest/googletest/include/gtest/gtest-printers.h:446:30: required from ‘void testing::internal::PrintTo(const T&, std::ostream*) [with T = std::type_index; std::ostream = std::basic_ostream]’
/home/john/googletest/googletest/include/gtest/gtest-printers.h:682:49: required from here
/usr/include/c++/10.2.0/ostream:773:5: error: no type named ‘type’ in ‘struct std::enable_if&>’
In file included from /home/john/googletest/googletest/include/gtest/internal/gtest-internal.h:57,
from /home/john/googletest/googletest/include/gtest/gtest.h:62,
from /home/john/gnucash-git/libgnucash/engine/test/gtest-gnc-rational.cpp:24:
/home/john/googletest/googletest/include/gtest/gtest-printers.h: In instantiation of ‘void testing::internal::PrintWithFallback(const T&, std::ostream*) [with T = std::type_index; std::ostream = std::basic_ostream]’:
/home/john/googletest/googletest/include/gtest/gtest-printers.h:446:30: required from ‘void testing::internal::PrintTo(const T&, std::ostream*) [with T = std::type_index; std::ostream = std::basic_ostream]’
/home/john/googletest/googletest/include/gtest/gtest-printers.h:682:49: required from here
/usr/include/c++/10.2.0/iomanip:79:5: note: candidate: ‘template std::basic_ostream<_Ch, _Tr>& std::operator<<(std::basic_ostream<_Ch, _Tr>&, std::_Resetiosflags)’
79 | operator<<(basic_ostream<_CharT, _Traits>& __os, _Resetiosflags __f)
| ^~~~~~~~
/usr/include/c++/10.2.0/iomanip:79:5: note: template argument deduction/substitution failed:
In file included from /home/john/googletest/googletest/include/gtest/gtest-matchers.h:44,
from /home/john/googletest/googletest/include/gtest/internal/gtest-death-test-internal.h:39,
from /home/john/googletest/googletest/include/gtest/gtest-death-test.h:41,
from /home/john/googletest/googletest/include/gtest/gtest.h:64,
from /home/john/gnucash-git/libgnucash/engine/test/gtest-gnc-rational.cpp:24:
/home/john/googletest/googletest/include/gtest/gtest-printers.h:216:33: note: cannot convert ‘std::declval()’ (type ‘const std::type_index’) to type ‘std::_Resetiosflags’
215 | typename = decltype(std::declval()
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
216 | << std::declval())>
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
```
Followed by a long list of SFINAE failure messages for every other overload of `operator<<`.

**Steps to reproduce the bug**

Get https://raw.githubusercontent.com/Gnucash/gnucash/maint/libgnucash/engine/gnc-int128.hpp
Create the following `gtest-test.cpp`:
```
#include
#include

int main()
{
GncInt128 f;
std::cout << f << std::endl;
}
```
compile with
```
g++ -I googletest/googletest/include/ gtest-test.cpp
```
Making any adjustments needed to find the two includes.

Commenting out line 279
```
std::ostream& operator<< (std::ostream&, const GncInt128&) noexcept;
```
will allow the compilation to succeed.

**Does the bug persist in the most recent commit?**

Yes.

**What operating system and version are you using?**

Arch Linux, fully updated yesterday. The problem was first discovered using Ubuntu 21.04 with their packaged googletest.

The problem does *not* reproduce on macOS 11.2 with Xcode 12.3's clang.

**What compiler and version are you using?**

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++,d --with-isl --with-linker-hash-style=gnu --with-system-zlib --enable-__cxa_atexit --enable-cet=auto --enable-checking=release --enable-clocale=gnu --enable-default-pie --enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object --enable-install-libiberty --enable-linker-build-id --enable-lto --enable-multilib --enable-plugin --enable-shared --enable-threads=posix --disable-libssp --disable-libstdcxx-pch --disable-libunwind-exceptions --disable-werror gdc_include_dir=/usr/include/dlang/gdc
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.2.0 (GCC)
**What build system are you using?**

N/A

**Additional context**

I have bisected the problem, it is caused by commit ac3c2a8d0496893787015014a5abd397b766cce2 "overload PrintTo for std::type_info and std::type_index" and reverting it allows compilation to complete normally.

Start with googletest/include/gtest/gtest-printers.h, especially the PrintWithFallback and PrintTo paths implicated in the GCC diagnostics, and inspect commit ac3c2a8d0496893787015014a5abd397b766cce2. Reproduce with gtest-test.cpp, gnc-int128.hpp, and GCC 10.2; done means the example compiles while retaining the GncInt128 stream overload.

Written by the indexing model from the issue text.