[PATCH] Support case insensitive header searches for MSVCCompat

[Ben Langmuir]

  Does the case-sensitivity behaviour really only apply to headers found in header search?  If not, then how about putting this in the virtual file system layer, or at least FileManager?

  Right now this doesn't cover the 'header' declarations in module map files (see ModuleMap.cpp, parseHeaderDecl).

http://llvm-reviews.chandlerc.com/D2972