Windows makefile library issue

[sammyfreg]

It seems like there's some issue with library extension handling for makefile project under windows.
Some internal logic seems to append a .a like it would be done on Linux.

Setup

• OS: Window 10
• Build: Makefile with gcc and clang
• This simple project demonstrate the issue : https://github.com/sammyfreg/hello-world
• Install the Chocolatey package manager (optional)
• Using Chocolatey, install make, gcc, clang for Windows (or pick other preferred method)
• Generate makefile projects by calling TestBuilb\Generate.bat
• Compile projects, using TestBuild\Build\MakefileBuildAll.bat
• Observe the errors tied to linking with the library project

Results

• GCC:
  I had to manually set the library extensions to '.a' in "TestBuild\Generate\shared.sharpmake.cs : 193".
  Otherwise the linking fails with filename prefixed with a 'lib' and postfixed with a '.a'
  xxx/bin/ld.exe: cannot find -l:libExampleLib_Release.lib.a
  This is because ExampleLib_Release.lib is outputed, but trying to link with libExampleLib_Release.lib.a.
• CLANG
  It fails even with the library extension set.
  (Error example when '.a' is not assigned in 'shared.sharpmake.cs : 193')
  LINK : fatal error LNK1181: cannot open input file ':libExampleLib_Retail.lib.a.lib'
  (Error example when '.a' is assigned in 'shared.sharpmake.cs : 193')
  LINK : fatal error LNK1181: cannot open input file ':ExampleLib_Release.a.lib'

Both problems seemed to be caused by the logic in Makefile::FixupLibraryNames()