Phobos test runner: Do not truncate pointer to 32bits

This is wrong for 64 bit targets. According to POSIX, the length is of
type int, but the pointer is a normal pointer type.

Author: jpf91

libphobos/testsuite/test_runner.d

@@ -40,7 +40,7 @@ bool printAll()
         if (m.unitTest)
         {
             string name = m.name;
-            printf("%.*s\n", cast(uint)name.length, cast(uint)name.ptr);
+            printf("%.*s\n", cast(int)name.length, name.ptr);
         }
     }
     return true;