Bug fix for Bugzilla bug 26602: Remove function bodies with KMP_ASSERT(0)

Fix for bugzilla https://llvm.org/bugs/show_bug.cgi?id=26602.  Removed functions
body consisted of the only KMP_ASSERT(0) statement.  Thus possible runtime crash
converted to compile-time error, which looks preferable (faster possible error
detection).

TODO: consider C++11 static assert as an alternative, that could
make the diagnostics better.

Patch by Andrey Churbanov

Differential Revision: http://reviews.llvm.org/D21304

llvm-svn: 272590