Makefile, ich_descriptors_tool/Makefile: unify behavior

ich_descriptors_tool/Makefile: have the same behavior as the main
flashrom Makefile
  - only set gcc explicit on MinGW HOST_OS
  - don't fallback to gcc if CC was not set
  - set CFLAGS and EXEC_SUFFIX for TARGET_OS, not for HOST_OS

Change-Id: I353c3de250167994a4aea1edfef57d839e900d78
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/58468
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72250
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2 files changed