Detect when the string "<::" is found in code after a cast or template name...

Detect when the string "<::" is found in code after a cast or template name and is interpreted as "[:" because of the digraph "<:". When found, give an error with a fix-it to add whitespace between the "<" and "::".

Patch by Richard Trieu! Plus a small tweak from me to deal with one of the tokens coming from a macro.

llvm-svn: 129540