tests/check/elements/audioconvert.c: Patch from #347221 adding a test for audioconvert channel remappings.

Original commit message from CVS:
* tests/check/elements/audioconvert.c: (get_float_mc_caps),
(get_int_mc_caps), (GST_START_TEST), (audioconvert_suite):
Patch from #347221 adding a test for audioconvert
channel remappings.