gpu: nvgpu: unit: enable signal handler in single thread

Until now, using single thread we disable the signal handler to
make it easier to debug crashes. Since we are now using single
threading in GVS, it is better to have the signal handler enabled
by default. This patch introduces a "-d" argument to explicitly
disable the signal handler and thus make local debugging easier.

JIRA NVGPU-2975

Change-Id: I35b0fb71990b3fef575242c1bba398a3b0e6facf
Signed-off-by: Nicolas Benech <nbenech@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2223662
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: svc-mobile-misra <svc-mobile-misra@nvidia.com>
Reviewed-by: svc-mobile-cert <svc-mobile-cert@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

userspace/include/unit/args.h

@@ -47,6 +47,7 @@ struct unit_fw_args {
 	bool		 nvtest;
 	bool		 is_qnx;
 	unsigned int	 test_lvl;
+	bool		 debug;
 	const char	*binary_name;
 
 	const char	*unit_name;