Fix #33518: Jack sync doesn't work in 2.64, 2.64 or 2.65 stable versions

Added new build option WITH_JACK_DYNLOAD for CMake and
WITH_BF_JACK_DYNLOAD for SCons, which means there'll be
no build-time linking against libjack and getting symbols
from libjack will happen runtime using dlopen and dlsym
tricks.

Alternative would be to use weak linking, but it'll require
having wrapper for preloading libjack.

This new options are disabled by default and they only
intended to be used on linux. Other platforms shall not
be using this and there shall be no functional changes
on non-linux platforms at all.

CMakeLists.txt

@@ -229,6 +229,9 @@ option(WITH_OPENCOLLADA		"Enable OpenCollada Support (http://www.opencollada.org
 option(WITH_SDL           "Enable SDL for sound and joystick support" ON)
 option(WITH_OPENAL        "Enable OpenAL Support (http://www.openal.org)" ON)
 option(WITH_JACK          "Enable Jack Support (http://www.jackaudio.org)" OFF)
+if(UNIX AND NOT APPLE)
+	option(WITH_JACK_DYNLOAD  "Enable runtime dynamic Jack libraries loading" OFF)
+endif()
 
 # Compression
 option(WITH_LZO           "Enable fast LZO compression (used for pointcache)" ON)
@@ -2202,6 +2205,7 @@ if(FIRST_RUN)
 	info_cfg_option(WITH_OPENAL)
 	info_cfg_option(WITH_SDL)
 	info_cfg_option(WITH_JACK)
+	info_cfg_option(WITH_JACK_DYNLOAD)
 	info_cfg_option(WITH_CODEC_AVI)
 	info_cfg_option(WITH_CODEC_FFMPEG)
 	info_cfg_option(WITH_CODEC_SNDFILE)