Fix commit c31a58b6565c3d6a3994cac8bfd9e9eac1a54c71.
Fix source file name comments
Fix NRE on invalid second attribute target
Fix SemaphoreSlim Constructor.

Fix https://bugzilla.xamarin.com/show_bug.cgi?id=11598.
Merge pull request #671 from Blewzman/master

Fix SemaphoreSlim
Fix returning uninitialized memory in get_pid_status_item ().
Disable some warnings when using clang.
Enable dolt on x64/osx.
Block task awaiter until task completes. Fixes #12745
Remove a pass from the llvm opt pipeline which is not a function pass.
[build]Fix make dist and use a symlink for mono.
Fix the build.
Add a missing case to mono_patch_info_hash ().