[clang] recognize hexagon-*-ld.lld variants (#117338)

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 resolve that symlink and consider it when determining lld-ness.

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

(cherry picked from commit 2dc0de7)

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).ends_with("ld.lld") ||
+           llvm::sys::path::stem(Exec).ends_with("ld.lld");
   bool UseShared = IsShared && !IsStatic;
   StringRef CpuVer = toolchains::HexagonToolChain::GetTargetCPUVersion(Args);