tests/testatk_vc.makin: Update a bit
tests/testatk_vc.makin: Update a bit

Change mentions of testglib_vc.mak and testpango_vc.mak in the message when
no CFG= is specified during invokation and have the CFLAGS match the ones
in Makefile.am better.

Distrotech/atk,Distrotech/atk,GNOME/at-spi2-core,GNOME/at-spi2-core,Distrotech/atk,GNOME/at-spi2-core