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/CMakeLists.txt

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+#
+# CMakeLists.txt
+# 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.
+
+cmake_minimum_required(VERSION 2.8.12)
+project(backward CXX)
+
+include(BackwardConfig.cmake)
+
+set(CMAKE_CXX_STANDARD_REQUIRED True)
+set(CMAKE_CXX_STANDARD 11)
+
+###############################################################################
+# COMPILER FLAGS
+###############################################################################
+
+if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" OR CMAKE_COMPILER_IS_GNUCXX)
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -pedantic-errors")
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g")
+endif()
+
+###############################################################################
+# BACKWARD OBJECT
+###############################################################################
+
+add_library(backward_object OBJECT backward.cpp)
+target_compile_definitions(backward_object PRIVATE ${BACKWARD_DEFINITIONS})
+target_include_directories(backward_object PRIVATE ${BACKWARD_INCLUDE_DIRS})
+set(BACKWARD_ENABLE $<TARGET_OBJECTS:backward_object> CACHE STRING
+	"Link with this object to setup backward automatically")
+
+
+###############################################################################
+# BACKWARD LIBRARY (Includes backward.cpp)
+###############################################################################
+option(BACKWARD_SHARED "Build dynamic backward-cpp shared lib" OFF)
+
+if(BACKWARD_SHARED)
+    set(libtype SHARED)
+endif()
+add_library(backward ${libtype} backward.cpp)
+target_compile_definitions(backward PUBLIC ${BACKWARD_DEFINITIONS})
+target_include_directories(backward PUBLIC ${BACKWARD_INCLUDE_DIRS})
+
+###############################################################################
+# TESTS
+###############################################################################
+
+if(BACKWARD_TESTS)
+	enable_testing()
+
+	add_library(test_main SHARED test/_test_main.cpp)
+
+	macro(backward_add_test src)
+		get_filename_component(name ${src} NAME_WE)
+		set(test_name "test_${name}")
+
+		add_executable(${test_name} ${src} ${ARGN})
+
+		target_link_libraries(${test_name} PRIVATE Backward::Backward test_main)
+
+		add_test(NAME ${name} COMMAND ${test_name})
+	endmacro()
+
+	# Tests without backward.cpp
+	set(TESTS
+		test
+		stacktrace
+		rectrace
+		select_signals
+		)
+
+	foreach(test ${TESTS})
+		backward_add_test(test/${test}.cpp)
+	endforeach()
+
+	# Tests with backward.cpp
+	set(TESTS
+		suicide
+		)
+
+	foreach(test ${TESTS})
+		backward_add_test(test/${test}.cpp ${BACKWARD_ENABLE})
+	endforeach()
+endif()
+
+install(
+    FILES "backward.hpp"
+    DESTINATION ${CMAKE_INSTALL_PREFIX}/include
+)
+install(
+    FILES "BackwardConfig.cmake"
+    DESTINATION ${CMAKE_INSTALL_PREFIX}/lib/backward
+)