re PR rtl-optimization/52139 (ICE: in remove_insn, at emit-rtl.c:3960 with -O -fPIC -fno-tree-dominator-opts -fno-tree-fre)

	PR rtl-optimization/52139
	* cfgrtl.c (cfg_layout_merge_blocks): If BB_END
	is a BARRIER after emit_insn_after_noloc, move BB_END
	to the last non-BARRIER insn before it.

	* gcc.dg/pr52139.c: New test.

From-SVN: r184005