[Driver] Use stem rather than filename for executable name

When comparing the linker name in Fuchsia driver, use stem rather
than filename to get the name of the linker becase on Windows, the
filename will have an extension.

Differential Revision: https://reviews.llvm.org/D25700

llvm-svn: 284430

clang/lib/Driver/Tools.cpp

@@ -10060,7 +10060,7 @@ void fuchsia::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   Args.ClaimAllArgs(options::OPT_w);
 
   const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
-  if (llvm::sys::path::filename(Exec).equals_lower("lld")) {
+  if (llvm::sys::path::stem(Exec).equals_lower("lld")) {
     CmdArgs.push_back("-flavor");
     CmdArgs.push_back("gnu");
   }