gcov.c: Add necessary instrumentation functions

(.text.ltp_interfaces_sem_unlink_2_2_main+0xd8): undefined reference to `__gcov_execlk'

Signed-off-by: wangmingrong1 <wangmingrong1@xiaomi.com>

libs/libbuiltin/libgcc/gcov.c

@@ -319,6 +319,10 @@ void __gcov_execve(void)
 {
 }
 
+void __gcov_execl(void)
+{
+}
+
 void __gcov_execv(void)
 {
 }