Created pal_consts.h. New exported functions are now prefixed with "snmalloc_".

src/pal/pal.h

@@ -1,5 +1,12 @@
 #pragma once
 
+#include "pal_consts.h"
+
+namespace snmalloc
+{
+  void error(const char* const str);
+}
+
 // If simultating OE, then we need the underlying platform
 #if !defined(OPEN_ENCLAVE) || defined(OPEN_ENCLAVE_SIMULATION)
 #  include "pal_apple.h"