Move GDB producer parsing routines to a separate file

Move GDB producer parsing routines to a separate file

gdb/ChangeLog:
2017-09-26  Walfred Tedeschi  <walfred.tedeschi@intel.com>

	* Makefile.in (SFILES): Add producer.c.
	(COMMON_OBS): Add producer.o
	* amd64-tdep.c (producer.h): Add new include.
	* dwarf2read.c (producer.h): Add new include.
	* producer.c: New file.
	* producer.h: New file.
	* utils.c (producer_is_gcc, producer_is_gcc_ge_4): Move to
	producer.c.
	* utils.h (producer_is_gcc, producer_is_gcc_ge_4): Move to
	producer.h.