ccanlint: remove empty statement warnings.

Since doesnt_matter() expands to nothing, GCC -Wextra suggests { }.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tools/ccanlint/tests/tests_pass.c

@@ -139,8 +139,9 @@ static void run_under_debugger(struct manifest *m, struct score *score)
 
 	command = tal_fmt(m, "gdb -ex 'break tap.c:139' -ex 'run' %s",
 			  first->file->compiled[COMPILE_NORMAL]);
-	if (system(command))
+	if (system(command)) {
 		doesnt_matter();
+	}
 }
 
 struct ccanlint tests_pass = {

tools/ccanlint/tests/tests_pass_valgrind.c

@@ -255,8 +255,9 @@ static void run_under_debugger_vg(struct manifest *m, struct score *score)
 			  concat(score, per_file_options(&tests_pass_valgrind,
 							 first->file)),
 			  valgrind_suppress, first->file->compiled[COMPILE_NORMAL]);
-	if (system(command))
+	if (system(command)) {
 		doesnt_matter();
+	}
 }
 
 struct ccanlint tests_pass_valgrind = {

tools/ccanlint/tests/tests_pass_without_features.c

@@ -56,8 +56,9 @@ static void run_under_debugger(struct manifest *m, struct score *score)
 
 	command = tal_fmt(m, "gdb -ex 'break tap.c:139' -ex 'run' %s",
 			  first->file->compiled[COMPILE_NOFEAT]);
-	if (system(command))
+	if (system(command)) {
 		doesnt_matter();
+	}
 }
 
 struct ccanlint tests_pass_without_features = {