Don't put a function's return type on its own line in Google style.

This would be against the style guide:
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Function_Declarations_and_Definitions#Function_Declarations_and_Definitions

Not sure what to do as a last resort if the function signature does not
fit onto a single line in Google style ..

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173690 91177308-0d34-0410-b5e6-96231b3b80d8