[clang] recognize hexagon-*-ld.lld variants

If we create a cross toolchain with a ${triple}-ld.lld symlink, clang finds
that symlink and when it uses it, it's not recognized as "lld".  Let's
consider it as lld as long as it ends in "ld.lld".

For example, clang provides hexagon-link specific link arguments such as
`-mcpu=hexagonv65` and `-march=hexagon` when hexagon-unknown-linux-musl-ld.lld
is found.  lld rejects this with the following error:

    hexagon-unknown-linux-musl-ld.lld: error: unknown emulation: cpu=hexagonv65

Author: androm3da

clang/lib/Driver/ToolChains/Hexagon.cpp

@@ -294,9 +294,10 @@ constructHexagonLinkArgs(Compilation &C, const JobAction &JA,
   bool IncStartFiles = !Args.hasArg(options::OPT_nostartfiles);
   bool IncDefLibs = !Args.hasArg(options::OPT_nodefaultlibs);
   bool UseG0 = false;
-  const char *Exec = Args.MakeArgString(HTC.GetLinkerPath());
-  bool UseLLD = (llvm::sys::path::filename(Exec).equals_insensitive("ld.lld") ||
-                 llvm::sys::path::stem(Exec).equals_insensitive("ld.lld"));
+  bool UseLLD = false;
+  const char *Exec = Args.MakeArgString(HTC.GetLinkerPath(&UseLLD));
+  UseLLD = UseLLD || llvm::sys::path::filename(Exec).endswith("ld.lld") ||
+           llvm::sys::path::stem(Exec).endswith("ld.lld");
   bool UseShared = IsShared && !IsStatic;
   StringRef CpuVer = toolchains::HexagonToolChain::GetTargetCPUVersion(Args);