Linux port: added libX11 to linked libraries.

Otherwise build fails on linux.
Merge pull request #2641 from sergey-shambir/fix_linux_linkage

Linux port: added libX11 to linked libraries.
issue #2161: android supports ETC format now
issue #2161: make linux,marmalade,native client,mac and emscripten project to include CCTextureETC.cpp
issue #2161:add CCTextureETC.cpp/.h into vs2010 project
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into ETC1-support
issue #2161: resolve conflict
Merge pull request #2654 from minggo/ETC1-support

Support ETC1 format on Android