[SPIN] Added the build script for Tizen Emulator (i586)

[SPIN] Added the build script for Tizen Emulator (i586)

Added the below changes for i586 build
- Added the build_emulator.sh file
- Added the ninja files
- Added the codes for i586 build in the gbs.conf file.
- Added the codes for i586 build in the chromiul-efl.spec file.
- Added the guide for i586 build in the Readme.md file.

Bug: http://107.108.218.239/bugzilla/show_bug.cgi?id=10509
Reviewed by: Piotr Tworek, Youngbok Yoon

Change-Id: If032bb14ce214914c196e8ad85f0a80b8ac71788
Signed-off-by: Youngcheol Kang <ychul.kang@samsung.com>