Add support for Amlogic G18 MX2 devices.

Conflicts:

	packages/lang/gcc/package.mk
	packages/linux/package.mk
Remove an invalid patch for GCC 4.7.3.
Update the patch for systemd, which adds missing enumeration values for Amlogic kernel.
Make kernel update work for devices that boot the kernel from NAND memory, such as Amlogic G18 MX2 devices.
Make flash_eraseall and nandwrite available in initramfs for kernel update to work properly.
Update kernel configuration file for Amlogic.
Add patches that fix some of the XBMC issues on Amlogic devices.
Add the amffmpeg, libamavutils and libamplayer libraries required for hardware decoding of video on Amlogic devices. Compile XBMC with amcodec support on Amlogic platform.
Add a patch to allow decoding of MPEG-2 SD video on Amlogic platform using hardware decoding.
Add support for Amlogic IR remotes.
Replace the ALSA sound output patch for Amlogic-based devices with another one

Previous sound-fixing patch for Amlogic caused problems (no sound) when using audio passthrough.
The new patch uses another approach that works well with audio passthrough.
Allow reboot only in shutdown menu on Amlogic.
Rename allow_reboot_only_in_shutdown_menu.patch into allow_only_reboot_in_shutdown_menu.patch
Remap some buttons of Amlogic IR remote

4 button         -> 4 key
Home button      -> Browser Home key
Return button    -> Escape key
Backspace button -> Backspace key
Power button     -> Power key
Add patch to make Browser Home key work in XBMC for Linux
Add patch to perform shutdown immediately on Power key press instead of showing shutdown menu
Build libamplayer from source code instead of using pre-built binaries
Compile framebuffer console on Amlogic as a kernel module and load it in initramfs

This helps us to make the Amlogic logo visible until initramfs will be loaded.
Otherwise the console overlaps the logo.
Disable librtmp support in amffmpeg because newer release of ffmpeg fails to build with it
Update logo in Amlogic installation package