SFN: don't drop markers for skipping var-tracking

SFN: don't drop markers for skipping var-tracking

Although debug markers are more useful when bind stmts are placed
among them, there is value in keeping them even when VTA limits are
exceeded.

for  gcc/ChangeLog

	PR debug/83422
	* var-tracking.c (vt_debug_insns_local): Do not drop markers.
	(variable_tracking_main_1): Keep markers even when VTA fails.

for  gcc/testsuite/ChangeLog

	PR debug/83422
	* gcc.dg/pr83422.c: New.

From-SVN: r255834