Import backtrace-cpp and integrate it into our main executable

Upstream release
https://github.com/bombela/backward-cpp/archive/v1.3.tar.gz

external/backtrace-cpp/test/select_signals.cpp

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+/*
+ * test/segfault.cpp
+ * Copyright 2013 Google Inc. All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "backward.hpp"
+
+#include <stdio.h>
+#include "test/test.hpp"
+
+using namespace backward;
+
+void badass_function() {
+	char* ptr = (char*)42;
+	*ptr = 42;
+}
+
+TEST_SEGFAULT (pprint_sigsev) {
+	std::vector<int> signals;
+	signals.push_back(SIGSEGV);
+	SignalHandling sh(signals);
+	std::cout << std::boolalpha << "sh.loaded() == " << sh.loaded() << std::endl;
+	badass_function();
+}
+
+TEST_SEGFAULT (wont_pprint) {
+	std::vector<int> signals;
+	signals.push_back(SIGABRT);
+	SignalHandling sh(signals);
+	std::cout << std::boolalpha << "sh.loaded() == " << sh.loaded() << std::endl;
+	badass_function();
+}