Adding option -fno-inline-asm to disallow inline asm

Summary:
This patch add a new option to dis-allow all inline asm.
Any GCC style inline asm will be reported as an error.

Reviewers: rnk, echristo

Reviewed By: rnk, echristo

Subscribers: bob.wilson, rnk, echristo, rsmith, cfe-commits

Differential Revision: http://reviews.llvm.org/D6870

llvm-svn: 226340