gdb/

gdb/
	* dwarf2read.c (dwarf2_get_pc_bounds): Require HIGH strictly higher
	than LOW.  Comment it.
	(read_partial_die): Call complaint for inappropriate zero LOWPC or
	HIGHPC not strictly higher than LOWPC.

gdb/testsuite/
	* gdb.dwarf2/dw2-empty-pc-range.S: New file.
	* gdb.dwarf2/dw2-empty-pc-range.exp: New file.
	* gdb.dwarf2/pr11465.S: New .text labels text_start and text_end.
	Provide a stub byte there.
	(DW_TAG_compile_unit): Set DW_AT_low_pc, DW_AT_high_pc and
	DW_AT_entry_pc.
	(dieb4, dieda): Set DW_AT_high_pc higher than DW_AT_low_pc.