The code added recently to enhance -Wmissing-format-attribute was
specific to the C frontend. This patch moves some of the code to
c-common.c and adds the necessary bits to the C++ frontend so that g++
also gets this enhancement.
I couldn't find a single spot in the C++ frontend to insert the code
like I did for C. Using 'convert_for_assignment' took care of assign,
init and return type, but I had to put an extra call in
'convert_for_arg_passing' to get function params. Any suggestion on a
single (or better) location would be much appreciated.
Also, the move to c-common.c consolidation is independent and can go
in separately (first) if the C++ bits need refining. I'm also going
to copy the C testcases over to the G++ testsuite. (Are there any
additional C++ cases we should cover beyond the four we did for C?)
Okay for mainline?