ada: Revert changing a GNATProve mode message to a non-warning

ada: Revert changing a GNATProve mode message to a non-warning

GNATProve compiles the program multiple times. During the
first run the warnings are suppressed. These messages need
to be suppressed during that run in order to avoid having
them duplicated in the following runs. Revert the previous
changes as there currently is not a way to simply suppress
info messages.

gcc/ada/

	* sem_res.adb (Resolve_Call): add warning insertion
	character into the info message.