configure.base: changed to 0.2.1, reworked the -D gathering for cflags gstreamer-config.in, gstreamer.pc.in, gstreame...

Original commit message from CVS:
configure.base: changed to 0.2.1, reworked the -D gathering for cflags
gstreamer-config.in, gstreamer.pc.in, gstreamer-uninstalled.pc.in:
reworked -D gathering for cflags