Tweaks to nhassert implementation. Change to warnings on MSC build.

sys/winnt/winnt.c

@@ -708,6 +708,23 @@ sys_random_seed(VOID_ARGS)
     }
     return ourseed;
 }
+
+/* nt_assert_failed is called when an nhassert's condition is false */
+void
+nt_assert_failed(expression, filepath, line)
+    const char * expression;
+    const char * filepath;
+    int line;
+{
+    const char * filename;
+
+    /* get file name from path */
+    filename = strrchr(filepath, '\\');
+    filename = (filename == NULL ? filepath : filename + 1);
+    impossible("nhassert(%s) failed in file '%s' at line %d",
+                expression, filename, line);
+}
+
 #endif /* WIN32 */
 
 /*winnt.c*/