merge_config.sh: exit on missing input files

Add a check for the existence of input files and exit (with failure)
if they are missing.

Without this additional check, missing files produce error messages
but still result in an output file being generated and a successful
exit code.

Change-Id: I8609e00ce99b491dcb1d41e64106a6829dc1fb41
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
1 file changed