tools: Add coccinelle script for checking against XMALLOC/XCALLOC NULLs

Signed-off-by: Donatas Abraitis <donatas.abraitis@gmail.com>

tools/coccinelle/xcalloc-xmalloc.cocci

@@ -0,0 +1,17 @@
+// No need checking against NULL for XMALLOC/XCALLOC.
+// If that happens, we have more problems with memory.
+
+@@
+type T;
+T *ptr;
+@@
+
+ptr =
+(
+XCALLOC(...)
+|
+XMALLOC(...)
+)
+...
+- if (ptr == NULL)
+- return ...;