We have in place support for parsing #pragma FENV_ACCESS, but that 
information is then discarded with a warning to the user that we don't 
support it.

This patch gets us one step closer by getting the info down into the 
AST in most cases.

Reviewed by:	rsmith
Differential Revision:	https://reviews.llvm.org/D49865

llvm-svn: 339693