if we die in IR generation of a compound statement, include

it in the stack trace, giving us stuff like:

Stack dump:
0.	Program arguments: clang t.c -emit-llvm 
1.	<eof> parser at end of file
2.	t.c:1:5: LLVM IR generation of declaration 'a'
3.	t.c:1:9: LLVM IR generation of compound statement ('{}')
4.	t.c:2:3: LLVM IR generation of compound statement ('{}')
Abort

llvm-svn: 66154