Capitalize 'Swift' in a comment

Author: gribozavr

stdlib/public/SwiftShims/FoundationShims.h

@@ -21,7 +21,7 @@
 
 //===--- Layout-compatible clones of Foundation structs -------------------===//
 // Ideally we would declare the same names as Foundation does, but
-// swift's module importer is not yet tolerant of the same struct
+// Swift's module importer is not yet tolerant of the same struct
 // coming in from two different Clang modules
 // (rdar://problem/16294674).  Instead, we copy the definitions here
 // and then do horrible unsafeBitCast trix to make them usable where required.