[Bug 56279] New: Wine fails to build if CC is set to the absolute path for the compiler

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=56279

Bug ID: 56279
           Summary: Wine fails to build if CC is set to the absolute path
                    for the compiler
           Product: Wine
           Version: unspecified
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

At least as of commit e607da943aa (win32u: Only queue a single IME update
during ImeProcessKey.), the Wine build fails if any of the [<ARCH>_]CC
environment variables are set to an absolute path to GCC/Clang, as opposed to
just the executable name. This can be reproduced by configuring and building
Wine with the follow environment variables:

export CC='/usr/bin/gcc'
export CROSSCC='/usr/bin/i686-w64-mingw32-gcc'
export i386_CC='/usr/bin/i686-w64-mingw32-gcc'
export x86_64_CC='55/usr/bin/x86_64-w64-mingw32-gcc'

The failure is specifically due to winebuild being provided an invalid target
specification argument (in this case, `/usr/bin/i686-w64-mingw32` instead of
`i686-w64-mingw32` ):

tools/winebuild/winebuild -w --staticlib -o
dlls/winecrt0/i386-windows/libwinecrt0.a -b /usr/bin/i686-w64-mingw32 \
...
winebuild: Unrecognized target '/usr/bin/i686-w64-mingw32'
make: *** [Makefile:167493: dlls/winecrt0/i386-windows/libwinecrt0.a] Error 1