gnu.cfg: Add "buffer-size" attribute and tests for xcalloc().

cfg/gnu.cfg

@@ -10,7 +10,7 @@
   </memory>
   <memory>
     <alloc init="false" buffer-size="malloc">xmalloc</alloc>
-    <alloc init="true">xcalloc</alloc>
+    <alloc init="true" buffer-size="calloc">xcalloc</alloc>
     <dealloc>free</dealloc>
   </memory>
   <!-- https://linux.die.net/man/3/backtrace -->

test/cfg/gnu.c

@@ -63,6 +63,14 @@ void bufferAccessOutOfBounds()
     sethostname(buf, 2);
     // cppcheck-suppress bufferAccessOutOfBounds
     sethostname(buf, 4);
+
+    // Declaration necessary because there is no specific / portable header containing xcalloc.
+    extern void *xcalloc(size_t nmemb, size_t size);
+    char * pAlloc1 = xcalloc(2, 4);
+    memset(pAlloc1, 0, 8);
+    // cppcheck-suppress bufferAccessOutOfBounds
+    memset(pAlloc1, 0, 9);
+    free(pAlloc1);
 }
 
 void leakReturnValNotUsed()