a ridiculous amount of propagation through the backend later,

a ridiculous amount of propagation through the backend later,
have the code generate slap a srcloc metadata on inline asm nodes.
This allows us to diagnose invalid inline asms with such nice
diagnostics as:

<inline asm>:1:2: error: unrecognized instruction
        abc incl    %eax
        ^
asm.c:2:12: note: generated from here
  __asm__ ("abc incl    %0" : "+r" (X));
           ^
2 diagnostics generated.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@100608 91177308-0d34-0410-b5e6-96231b3b80d8