e comp - wl - add void cast to reduce warnings

we're pointer playing anyway so types here are not really useful. we
have to get our ptrs right - including alignment, and these warnings
are not useful and just noise.

src/bin/e_comp_wl.h

@@ -39,7 +39,7 @@
 #  define container_of(ptr, type, member) \
    ({ \
       const __typeof__( ((type *)0)->member ) *__mptr = (ptr); \
-      (type *)( (char *)__mptr - offsetof(type,member) ); \
+      (type *)(void *)( (char *)__mptr - offsetof(type,member) ); \
    })
 
 typedef struct _E_Comp_Wl_Buffer E_Comp_Wl_Buffer;