rename PrettyStackTraceDecl -> PrettyStackTraceActionsDecl.
Introduce a new PrettyStackTraceDecl.
Use it to add the top level LLVM IR generation stuff in 
Backend.cpp to stack traces.  We now get crashes 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'
Abort

for IR generation crashes.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@66153 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed