Boost can't be successfully configured to use ICU backend on Windows

When I attempt to use ICU as the internationalization backend for boost::locale and regex, the configure test always fails.

Digging down it seems as though the test requires debug libraries to be present, as well as release libraries.

ICU (on windows) builds it's dlls and lib files with a `d` suffix to denote "Debug", so it should be able to build and link against either a debug or a release build.

I've reproduced this is 1.75.0 and releases back to 1.72.0

Here is a bit of the relevant config.log from a boost 1.74.0 release build.
```
file C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu_obj.obj.rsp
"libs\locale\src\..\build\has_icu_test.cpp" -Fo"C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu_obj.obj" -TP /Z7 /Od /Ob0 /W3 /GR /MDd /Zc:forScope /Zc:wchar_t /Zc:inline /Zc:throwingNew /favor:blend /wd4675 /EHs /std:c++14 -c
-DBOOST_ALL_NO_LIB=1
"-I."
"-IC:\Users\robb\.conan\data\icu\68.2\_\_\package\611fcefb561f89074ece4ede322b83bfae850b30\include"
compile-c-c++ C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu_obj.obj

call "C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\standalone\msvc\1516fc4ab8d17a0765a1f78ddebd56c2\msvc-setup.bat" >nul
cl /Zm800 -nologo @"C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu_obj.obj.rsp"

has_icu_test.cpp

file C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu.exe.rsp

"C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu_obj.obj"
"icudt.lib"
"icuind.lib"
"icuucd.lib"
msvc.link C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu.exe

call "C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\standalone\msvc\1516fc4ab8d17a0765a1f78ddebd56c2\msvc-setup.bat" >nul
link /NOLOGO /INCREMENTAL:NO /DEBUG /MACHINE:X64 /MANIFEST:EMBED /subsystem:console /out:"C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu.exe" /LIBPATH:"C:\Users\robb\.conan\data\icu\68.2\_\_\package\611fcefb561f89074ece4ede322b83bfae850b30\lib" @"C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu.exe.rsp"

LINK : fatal error LNK1181: cannot open input file 'icuind.lib'
...failed msvc.link C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu.exe C:\Users\robb\.conan\data\boost\1.74.0\_\_\build\491db9cc8564376c4db3d2f68ad28bbc2648a5a4\boost\bin.v2\libs\locale\build\aa5f60dfd728cc291a7e1357df68268d\has_icu.pdb...
...failed updating 2 targets...
...updated 4 targets...
```