mysql_config --cflags gave a flag that forced the HP/UX
C++ compiler into C-mode; as a result, C++ sources could
not be compiled correctly.

We now filter out the offending flag (like we do for Sun)
so that --cflags will work for both C and C++.


scripts/mysql_config.sh:
  Add -AC99 (for HP/UX) to the list of flags we need to remove
  from "mysql_config --cflags" so they work for C and C++ both.