stylistic changes to CFG.cpp

Clang Frontend
#1

Hi Ted,

Per your comment, I'm putting the stylistic changes to CFG.cpp in a
separate patch. Please see
http://codereview.appspot.com/3245042

I did two things in this patch:

1. "no 'else' after 'return'" -- this is for conformance with the
coding standards.

2. move 'else' to the line of the previous '}' -- this is for consistency.

All tests pass. Thanks,

#2

Looks great.

#3

Thanks! Committed in r119983.