tests/check/generic/states.c: Copy the current generic/states example from -base...

tests/check/generic/states.c: Copy the current generic/states example from -base and adapt so we can use the exact sa...

Original commit message from CVS:
* tests/check/generic/states.c: (GST_START_TEST), (states_suite):
Copy the current generic/states example from -base and adapt so
we can use the exact same code everywhere.
Check a STATES_IGNORE_ELEMENTS env var which can be used
to ignore certain element factories for this test, which is
what is being done in -base
* tests/check/Makefile.am:
Mention this environment variable.