When forming the !srcloc mdnode for an inline asm, add the SourceLocations

of all the lines of the inline asm.  With the refactoring and enhancement
of the backend, we can now reports errors on the correct source line when
an asm contains multiple lines of text.  For something like this:

void foo() {
  asm("push %rax\n"
      ".code32\n");
}

we used to get this: (note that the line 4 in t.c isn't helpful)

t.c:4:7: error: warning: ignoring directive for now
  asm("push %rax\n"
      ^
<inline asm>:2:1: note: instantiated into assembly here
.code32
^

now we get:

t.c:5:8: error: warning: ignoring directive for now
      ".code32\n"
       ^
<inline asm>:2:1: note: instantiated into assembly here
.code32
^

Note that we're pointing to line 5 properly now.  This implements
rdar://7839391 - inline asm errors should point to the right line in the asm
and makes the error message in PR8595 much less confusing.

llvm-svn: 119489