fix the inline asm diagnostics to emit the error on the primary

source code location instead of on the note.  Previously we generated:

<inline asm>:1:2: error: unrecognized instruction
        barf
        ^
t.c:4:8: note: generated from here
  asm ("barf");
       ^

Now we generate:

t.c:4:8: error: unrecognized instruction
  asm ("barf");
       ^
<inline asm>:1:2: note: instantated into assembly here
        barf
        ^

llvm-svn: 105978