1. Respect CXXFLAGS
2. Switch Clementine to FindBacktrace.cmake

Index: ext/libclementine-common/CMakeLists.txt
--- ext/libclementine-common/CMakeLists.txt.orig
+++ ext/libclementine-common/CMakeLists.txt
@@ -2,7 +2,7 @@ include_directories(${PROTOBUF_INCLUDE_DIRS})
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
 include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --std=c++0x")
+set(CMAKE_CXX_FLAGS "--std=c++0x ${CMAKE_CXX_FLAGS}")
 
 set(SOURCES
   core/closure.cpp
@@ -39,6 +39,14 @@ target_link_libraries(libclementine-common
   ${TAGLIB_LIBRARIES}
   ${CMAKE_THREAD_LIBS_INIT}
 )
+
+find_package(Backtrace)
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/config.h.in
+               ${CMAKE_CURRENT_BINARY_DIR}/config.h)
+if(Backtrace_FOUND)
+  include_directories(${Backtrace_INCLUDE_DIRS})
+  target_link_libraries(libclementine-common ${Backtrace_LIBRARIES})
+endif(Backtrace_FOUND)
 
 find_package(Backtrace)
 configure_file(core/conf_backtrace.h.in conf_backtrace.h)
