FLAC failed to build due to error C2375 on windows with MSVC

[spacelg]

Environment:
Windows Server 2016 + VS2017 + flac master branch latest source code.

Issue description:
I tried to build flac using VS2017 on Windows Server 2016. We found that flac failed to build due to error C2375: 'flac_internal_set_utf8_filenames': redefinition; different linkage. It can be first reproduced on b917d45 revision. Could you please help take a look at this? Thanks in advance!

Repro steps:

1. git clone https://github.com/xiph/flac D:\FLAC\src
2. Open a VS 2017 x86 command prompt as admin and browse to D:\FLAC\src
3. devenv /upgrade FLAC.sln
4. msbuild FLAC.sln /t:Rebuild /p:Configuration=Release;Platform=Win32 /p:WindowsTargetPlatformVersion=10.0.17134.0

log_x86_build.log

Actual result:
D:\FLAC\src\src\libFLAC\windows_unicode_filenames.c(67): error C2375: 'flac_internal_set_utf8_filenames': redefinition; different linkage [D:\FLAC\src\src\libFLAC\libFLAC_dynamic.vcxproj]
D:\FLAC\src\src\libFLAC\windows_unicode_filenames.c(72): error C2375: 'flac_internal_get_utf8_filenames': redefinition; different linkage [D:\FLAC\src\src\libFLAC\libFLAC_dynamic.vcxproj]
D:\FLAC\src\src\libFLAC\windows_unicode_filenames.c(79): error C2375: 'flac_internal_fopen_utf8': redefinition; different linkage [D:\FLAC\src\src\libFLAC\libFLAC_dynamic.vcxproj]
D:\FLAC\src\src\libFLAC\windows_unicode_filenames.c(101): error C2375: 'flac_internal_stat64_utf8': redefinition; different linkage [D:\FLAC\src\src\libFLAC\libFLAC_dynamic.vcxproj]
D:\FLAC\src\src\libFLAC\windows_unicode_filenames.c(117): error C2375: 'flac_internal_chmod_utf8': redefinition; different linkage [D:\FLAC\src\src\libFLAC\libFLAC_dynamic.vcxproj]
D:\FLAC\src\src\libFLAC\windows_unicode_filenames.c(133): error C2375: 'flac_internal_utime_utf8': redefinition; different linkage [D:\FLAC\src\src\libFLAC\libFLAC_dynamic.vcxproj]
D:\FLAC\src\src\libFLAC\windows_unicode_filenames.c(152): error C2375: 'flac_internal_unlink_utf8': redefinition; different linkage [D:\FLAC\src\src\libFLAC\libFLAC_dynamic.vcxproj]

[erikd]

@evpobr ?

[evpobr]

Open a VS 2017 x86 command prompt as admin and browse to D:\FLAC\src

@spacelg , correct me if i wrong - we are talking about FLAC.sln in root directory, not CMake generated one? I don't see FLAC.sln in src/ directory.

[sezero]

Does the attached patch help?

patch.txt

[sezero]

See #153