[MSVCToolChain] Guard hardcoded Windows paths with LLVM_ON_WIN32

Paths like C:/foo will never work on UNIX platforms, don't bother
implicitly adding them to the search path.

llvm-svn: 276606

clang/lib/Driver/MSVCToolChain.cpp

@@ -648,6 +648,7 @@ void MSVCToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
     return;
   }
 
+#if defined(LLVM_ON_WIN32)
   // As a fallback, select default install paths.
   // FIXME: Don't guess drives and paths like this on Windows.
   const StringRef Paths[] = {
@@ -658,6 +659,7 @@ void MSVCToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
     "C:/Program Files/Microsoft Visual Studio 8/VC/PlatformSDK/Include"
   };
   addSystemIncludes(DriverArgs, CC1Args, Paths);
+#endif
 }
 
 void MSVCToolChain::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,