[libcxxabi] [test] Don't cast a pointer to long, fixing the test on Windows

[mstorsjo]

Summary

Use uintptr_t instead. On Windows, long is 32 bit even on 64 bit
architectures.

libcxxabi/test/catch_ptr_02.pass.cpp

 // an earlier handler of type 'Base'. Congrats, you've just diagnosed the
 // behavior under test.
 // ADDITIONAL_COMPILE_FLAGS: -Wno-exceptions
 
 // The fix for PR17222 made it in the dylib for macOS 10.10
 // XFAIL: stdlib=apple-libc++ && target={{.+}}-apple-macosx10.9
 
 #include <cassert>
+#include <stdint.h>
 
 #if __cplusplus < 201103L
 #define DISABLE_NULLPTR_TESTS
 #endif
 
 struct  A {};
 A a;
 const A ca = A();

 void test7 ()
 {
     try
     {
         throw (derived*)12;
         assert(false);
     }
     catch (base2 *p) {
-        assert ((unsigned long)p == 12+sizeof(base1));
+        assert ((uintptr_t)p == 12+sizeof(base1));
     }
     catch (...)
     {
         assert (false);
     }
 }