lib: newlib: fix _gettimeofday hook

The time() function works correctly with the minimal libc, but always
returns -1 with the newlib libc. This is due to the _gettimeofday hook
being implemented that way.

Fix that by calling gettimeofday in the _gettimeofday hook instead of
returning -1.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

lib/libc/newlib/libc-hooks.c

@@ -18,6 +18,7 @@
 #include <sys/sem.h>
 #include <sys/mutex.h>
 #include <sys/mem_manage.h>
+#include <sys/time.h>
 
 #define LIBC_BSS	K_APP_BMEM(z_libc_partition)
 #define LIBC_DATA	K_APP_DMEM(z_libc_partition)
@@ -402,12 +403,7 @@ void *_sbrk_r(struct _reent *r, int count)
 }
 #endif /* CONFIG_XTENSA */
 
-struct timeval;
-
 int _gettimeofday(struct timeval *__tp, void *__tzp)
 {
-	ARG_UNUSED(__tp);
-	ARG_UNUSED(__tzp);
-
-	return -1;
+	return gettimeofday(__tp, __tzp);
 }