Correctly parse GCC-style asm line following MS-style asm line.

Quit parsing MS-style inline assembly if the following statement has GCC style.
Enables compilation of code like

void f() {
  __asm mov ebx, ecx
  __asm__("movl %ecx, %edx");
}

Differential Revision: http://reviews.llvm.org/D18652

llvm-svn: 266976