meson: Use new names for flex/bison configuration data
meson: Use new names for flex/bison configuration data

Re-using 'cdata' clobbers the global cdata variable that is used everywhere
else. This was noticed because it was clobbering cdata values in
libs/gst/check/libcheck/meson.build and causing the tests to fail because
clock_gettime was getting overriden in libcheck.a that links with the tests

centricular/gstreamer,centricular/gstreamer,centricular/gstreamer,centricular/gstreamer,centricular/gstreamer