Minus a bunch of warnings when enabling alloca()

libcelt/stack_alloc.h

@@ -105,7 +105,7 @@
 #define ALLOC(var, size, type) type var[size]
 #elif defined(USE_ALLOCA)
 #define VARDECL(var) var
-#define ALLOC(var, size, type) var = alloca(sizeof(type)*(size))
+#define ALLOC(var, size, type) var = ((type*)alloca(sizeof(type)*(size)))
 #else
 /*#define VARDECL(var) var
 #define ALLOC(var, size, type) var = PUSH(stack, size, type)*/