Add an _LIBCPP_NORETURN inline function named __throw_XXX for each exception...

Add an _LIBCPP_NORETURN inline function named __throw_XXX for each exception type we define. They either construct and throw the exception, or abort() (if exceptions are disabled). Use these functions everywhere instead of assert()ing when exceptions are disabled. WARNING: This is a behavior change - but only with exceptions disabled.  Reviewed as: https://reviews.llvm.org/D23855.

llvm-svn: 279744