tests/mem_alloc: Eliminate alloc warnings. Define _BSD_SOURCE

We need to keep gcc from complaining about large calloc/malloc/realloc
sizes as that's what we're testing.

Define _BSD_SOURCE so that libraries sharing the glibc convention (like
newlib and picolibc) for controlling the API level visible to applications
will declare reallocarray(3), which is an OpenBSD extension to the C
library.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

tests/lib/mem_alloc/src/main.c

@@ -16,6 +16,15 @@
  * it guarantee that ALL functionality provided is working correctly.
  */
 
+#if defined(__GNUC__)
+/*
+ * Don't complain about ridiculous alloc size requests
+ */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Walloc-size-larger-than="
+#endif
+
+#define _BSD_SOURCE
 #include <zephyr/zephyr.h>
 #include <ztest.h>
 #include <stdlib.h>