[PATCH] [AArch64] Implement Clang CLI interface proposal about "-march".

[Kristof Beyls]

I think there's one more missing test or set of tests, to cover this sentence from the documentation of the -mcpu option:
"Where this option is used in conjunction with -march or -mtune, those options take precedence over the appropriate part of this option."

Apart from that, this patch looks good to me.

================
Comment at: lib/Driver/Tools.cpp:1568
@@ +1567,3 @@
+
+// Handle -march=.
+static void getAArch64FeaturesFromMtune(const Driver &D, StringRef Mtune,
----------------
-march -> -mtune in the comment.
TBH, I don't think these comments add much value, the name of the functions are descriptive enough.

http://reviews.llvm.org/D4346