Formatting: In @implementation etc lines, put a space before protocol lists.

Don't do this in Google style though:
http://google-styleguide.googlecode.com/svn/trunk/objcguide.xml#Protocols

Most other places (function declarations, variable declarations) still get
this wrong, and since this looks very similiar to template instantiations to
the lexer (`id <MyProtocol> a = ...`), it's going to be hard to fix in some
places.

llvm-svn: 172099