Some more enhancements to test0

- Only the topmost parent prints pass messages. Any failed child can print fail message.
- Added testing of 16 forked threads doing file create/read/write/close and
  16 forked x 4 cloned = 64 threads spawning/exiting

tasks/test0/include/tests.h

@@ -3,13 +3,15 @@
 
 #define __TASKNAME__			"test0"
 
-// #define TEST_VERBOSE_PRINT
+//#define TEST_VERBOSE_PRINT
 #if defined (TEST_VERBOSE_PRINT)
 #define test_printf(...)	printf(__VA_ARGS__)
 #else
 #define test_printf(...)
 #endif
 
+#include <sys/types.h>
+extern pid_t parent_of_all;
 
 int shmtest(void);
 int forktest(void);