mkelfImage: Use -fno-stack-protector if supported by gcc

mkelfImage: Use -fno-stack-protector if supported by gcc

Gcc 4.1 comes with an SSP https://wiki.ubuntu.com/GccSsp
This is disabled to work around '__stack_chk_fail' symbol not found failures
http://www.coreboot.org/FAQ/Obsolete#How_do_I_fix_stack_chk_fail_errors.3F

The presence of -fno-stack-protector is tested for automatically by configure.

Change-Id: I28ef158829f5935f985cfd5a5440733685cf479a
Reported-by: Raymond Danks <raymonddanks@gmail.com>
Signed-off-by: Raymond Danks <raymonddanks@gmail.com>
Reviewed-on: http://review.coreboot.org/112
Tested-by: build bot (Jenkins)
Reviewed-by: Peter Stuge <peter@stuge.se>