cfgcleanup.c (outgoing_edges_match, [...]): Remove CASE_DROPS_THROUGH checks, it is never defined.

	* cfgcleanup.c (outgoing_edges_match, try_crossjump_to_edge):
	Remove CASE_DROPS_THROUGH checks, it is never defined.
	* cfglyout.c (fixup_reorder_chain): Likewise.
	* cfgrtl.c (rtl_verify_flow_info): Likewise.
	* stmt.c (expand_case): Likewise.
	* cfgbuild.c (make_edges): Likewise.  Also remove force_fallthru,
	it is now always 0.
	* system.h (CASE_DROPS_THROUGH): Poison.
	* doc/md.texi (casesi): Remove documentation of CASE_DROPS_THROUGH.
	* doc/tm.texi (casesi): Remove documentation of CASE_DROPS_THROUGH.

	* config/v850/v850.h: Remove commented out CASE_DROPS_THROUGH.

From-SVN: r91488