perform size checks on various operations

Signed-off-by: Tavi <tavi@divested.dev>
Co-authored-by: =?UTF-8?q?Christian=20G=C3=B6ttsche?= <cgzones@googlemail.com>

test/wmemmove_buffer_overflow.c

@@ -0,0 +1,15 @@
+#include <stdlib.h>
+#include <wchar.h>
+
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    wchar_t *firstbuffer = malloc(16 * sizeof(wchar_t));
+    wchar_t *secondbuffer = malloc(32 * sizeof(wchar_t));
+    if (!firstbuffer && !secondbuffer) {
+        return 1;
+    }
+    wmemset(secondbuffer, L'\U0001F642', 32);
+    wmemmove(firstbuffer, secondbuffer, 32);
+    return 1;
+}