Fix a bug PlatformDarwin::SDKSupportsModule.
This fixes a bug PlatformDarwin::SDKSupportsModule introduced by
https://reviews.llvm.org/D47889. VersionTuple::tryParse() can deal
with an optional third (micro) component, but the parse will fail when
there are extra characters after the version number (e.g.: trying to
parse the substring "12.0.sdk" out of "iPhoneSimulator12.0.sdk" fails
after that patch). Fixed here by stripping the ".sdk" suffix first.
(Part of) rdar://problem/
45041492
Differential Revision https://reviews.llvm.org/D53677
llvm-svn: 345274