tests: print error locations verbosely

So we don't have to figure out which line generated this error by
searching for the subtest/error code combination.

Change-Id: Icca0a776fd19f0f3d250ddb76916f5f932dd9b5e

test/test3.c

@@ -25,7 +25,6 @@ void test3a(void);
 void test3c(void);
 void test3d(void);
 void test3e(void);
-void e(int n);
 
 int main(argc, argv)
 int argc;