[PATCH] Driver: enhance MSC version compatibility

[Reid Kleckner]

================
Comment at: lib/Basic/Targets.cpp:582
@@ +581,3 @@
+    // Ideally, the -fmsc-version would take a period delimited component of the
+    // form MM.mm.bbbbb.pp (e.g. 17.00.60610.1).  Unfortunately, the current
+    // limitation of 32-bits prevents the encoding of Patch.  Assume that patch
----------------
I'm not crazy about -fmsc-version=MMmmmbbbbb.  How about -fmsc-version either takes a non-full number, or it takes a dot-separated number as described here?  We can skip the patch version for now, since that's too many bits.

http://reviews.llvm.org/D4233