Add forgotten return value test

src/ttail_search_files.c

 					break;
 				}
 				cur_off += r;
-				write(out, ttail_file_getline_buf(t),
+				r = write(out, ttail_file_getline_buf(t),
 					strlen(ttail_file_getline_buf(t)));
+				if(r == -1)
+				{
+					perror("unable to write");
+					return;
+				}
 			}
 			else
 			{

tests/ttail_check.h

 int main(int argc, char **argv) {\
 	int n_fail;\
 	SRunner *sr;\
-	chdir(dirname(argv[0])); /* move in ./tests dir */ \
+	n_fail = chdir(dirname(argv[0])); /* move in ./tests dir */ \
+	if(n_fail < 0)\
+	{\
+		perror("Unable to chdir in tests folder");\
+	}\
 	sr = srunner_create(ttail_test_suite());\
 	srunner_set_fork_status(sr, CK_FORK);\
 	srunner_run_all(sr, CK_VERBOSE);\