Added first pass at shrinkler example

tools/external/shrinkler/assert.h

@@ -0,0 +1,37 @@
+// Copyright 1999-2015 Aske Simon Christensen. See LICENSE.txt for usage terms.
+
+/*
+
+An assert function which contains a breakpoint, for ease of debugging.
+
+*/
+
+#pragma once
+
+void internal_error() {
+	fflush(stdout);
+	fprintf(stderr,
+		"\n\nShrinkler has encountered an internal error.\n"
+		"Please send a bug report to blueberry@loonies.dk,\n"
+		"providing the file you tried to compress.\n"
+		"\n"
+		"Thanks, and apologies for the inconvenience.\n\n");
+	fflush(stderr);
+	exit(1);
+}
+
+#ifndef NDEBUG
+#include <stdio.h>
+static void _assert_func(const char *file, int line, const char *exp) {
+	fflush(stdout);
+	fprintf(stderr, "\n\nassertion \"%s\" failed: file \"%s\", line %d\n", exp, file, line);
+	fflush(stderr);
+#ifdef DEBUG
+	__asm volatile ("int3;");
+#endif
+	internal_error();
+}
+#undef assert
+#define assert(__e) ((__e) ? (void)0 : _assert_func (__FILE__, __LINE__, #__e))
+#endif
+