re PR debug/54499 (GCC produces wrong debugging information, failure while assembling generated .s file)

	PR debug/54499
	* cgraphunit.c (assemble_thunk): Don't call source_line debug hook
	here, instead call insn_locations_{init,finalize} and initialize
	prologue_location.

	* g++.dg/debug/pr54499.C: New test.

From-SVN: r193338