cannot build on Solaris 11 64-bit sparc due to libutil not found

My understanding is that Solaris has no such library, but boost does not have a check to determine whether or not to link it. It just always does.
```
gcc.link.dll bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/libboost_python27.so.1.75.0
ld: fatal: library -lutil: not found
collect2: error: ld returned 1 exit status

"g++" -o "bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-
hidden/libboost_python27.so.1.75.0" -Wl,-h -Wl,libboost_python27.so.1.75.0 -shared -Wl,--start-group
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/list.o" "bin.v2/libs/python/build/gcc-
10.2.0/release/python-2.7/threading-multi/visibility-hidden/long.o" "bin.v2/libs/python/build/gcc-10.2.0/release/python-
2.7/threading-multi/visibility-hidden/dict.o" "bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-
hidden/tuple.o" "bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/str.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/slice.o" "bin.v2/libs/python/build/gcc-
10.2.0/release/python-2.7/threading-multi/visibility-hidden/converter/from_python.o" "bin.v2/libs/python/build/gcc-
10.2.0/release/python-2.7/threading-multi/visibility-hidden/converter/registry.o" "bin.v2/libs/python/build/gcc-
10.2.0/release/python-2.7/threading-multi/visibility-hidden/converter/type_id.o" "bin.v2/libs/python/build/gcc-
10.2.0/release/python-2.7/threading-multi/visibility-hidden/object/enum.o" "bin.v2/libs/python/build/gcc-
10.2.0/release/python-2.7/threading-multi/visibility-hidden/object/class.o" "bin.v2/libs/python/build/gcc-10.2.0/release/python-
2.7/threading-multi/visibility-hidden/object/function.o" "bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-
multi/visibility-hidden/object/inheritance.o" "bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-
hidden/object/life_support.o" "bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-
hidden/object/pickle_support.o" "bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-
hidden/errors.o" "bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/module.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/converter/builtin_converters.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/converter/arg_to_python_base.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/object/iterator.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/object/stl_iterator.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/object_protocol.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/object_operators.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/wrapper.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/import.o"
"bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-hidden/exec.o" "bin.v2/libs/python/build/gcc-
10.2.0/release/python-2.7/threading-multi/visibility-hidden/object/function_doc_signature.o" -Wl,-Bstatic -Wl,-Bdynamic -lrt -
ldl -lpthread -lutil -Wl,--end-group -fPIC -m64 -pthread -fvisibility=hidden -fvisibility-inlines-hidden -mcpu=v7

...failed gcc.link.dll bin.v2/libs/python/build/gcc-10.2.0/release/python-2.7/threading-multi/visibility-
hidden/libboost_python27.so.1.75.0...
```