Hunk #3: ensure that libexecinfo symbols are resolved (fix the build on ld.bfd archs)

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -59,9 +59,7 @@ if(NOT CPACK_GENERATOR AND NOT CMAKE_INSTALL_RPATH AND
 	message(STATUS "Setting install rpath to ${CMAKE_INSTALL_RPATH}")
 endif()
 
-if(APPLE)
-	find_package(Iconv REQUIRED)
-endif()
+find_package(Iconv REQUIRED)
 
 if(ENABLE_MBEDTLS)
 	message(STATUS "MBEDTLS Enabled")
@@ -128,7 +126,8 @@ check_library_exists("dl" "dladdr" "" HAVE_LIBDL)
 if(ANDROID)
 	set(HAVE_EXECINFO 0)
 else()
-	check_include_file("execinfo.h" HAVE_EXECINFO)
+	check_library_exists("execinfo" "backtrace" "" HAVE_EXECINFO)
+	SET(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -lexecinfo")
 endif()
 
 configure_file("${CMAKE_CURRENT_SOURCE_DIR}/config.h.cmake" "${CMAKE_CURRENT_BINARY_DIR}/config.h")
