* gdb.threads/gcore-thread.exp: Use gdb_gcore_cmd.

	* gdb.threads/gcore-thread.exp: Use gdb_gcore_cmd.
	* gdb.python/py-strfns.exp (test_strfns_core_file): Use
	gdb_gcore_cmd.
	* gdb.cell/gcore.exp: Use gdb_gcore_cmd.
	* gdb.base/gcore.exp: Use gdb_gcore_cmd.
	* gdb.base/gcore-relro.exp: Use gdb_gcore_cmd.
	* gdb.base/gcore-buffer-overflow.exp: Use gdb_gcore_cmd.
	* gdb.base/auxv.exp: Use gdb_gcore_cmd.
	* gdb.arch/vsx-regs.exp: Use gdb_gcore_cmd.
	* gdb.arch/system-gcore.exp: Use gdb_gcore_cmd.
	* gdb.arch/pa-nullify.exp (test_core_bt): Use gdb_gcore_cmd.
	* lib/gdb.exp (gdb_gcore_cmd): New proc.