[xbuild] Actually delete common files (CopyLocal) during Clean.

The common files that should be deleted during Clean (see 4c37deb)
weren't actually written to the CleanFile, as they were stored in
FileWrites after it was already used to create CombinedFileWrites.
Fix for bug 12892 - Path.GetFullPath() may return incorrect relative path under Windows
Merge pull request #676 from TalAloni/master

Fix for bug 12892 - Path.GetFullPath() may return incorrect relative path under Windows
Another go fighting autohell.
Cleanup automake warnings.
Fix the build if -j4 is used.
Handle unicode line separators when parsing C# files
Fix generated generated code for implicit nullable conversions involving numeric binary promotion
[Mono.Debugger.Soft] More specific exception when not suspended
Merge pull request #642 from Ventero/CleanCopyLocal

[xbuild] Actually delete common files (CopyLocal) during Clean.
Remove debug spew from switch_gc.
Emit the thumb plt trampolines as binary since clang has trouble encoding the assembly.
Call correct ApplyToExtraTarget base override. Fixes #12949
[Mono.Cairo] Don't log warnings during VM shutdown

Else it can explode pretty badly if the Console streams are
finalized before the Cairo objects.
Fix more thumb+clang problems.
Tweak tokenizer get_char.