libmojo: Catch more exceptions in callbacks

This change catches another place where unhandled exceptions would
become fatal for system_server: the QueryVersion callback. It instead
converts the exception into an WTF log.

Bug: 28986534
Bug: 64805573
Test: m
Change-Id: Ic1a0e9892b96839c7afa1244a33ff37c19962641
1 file changed