Documentation/accounting/getdelays.c: add missing null-terminate after strncpy call

Added a guaranteed null-terminate after call to strncpy.

This was partly found using a static code analysis program called
cppcheck.
Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/accounting/getdelays.c

@@ -314,6 +314,7 @@ int main(int argc, char *argv[])
 			break;
 		case 'm':
 			strncpy(cpumask, optarg, sizeof(cpumask));
+			cpumask[sizeof(cpumask) - 1] = '\0';
 			maskset = 1;
 			printf("cpumask %s maskset %d\n", cpumask, maskset);
 			break;