[EFL] Unable to do make install since r171901
https://bugs.webkit.org/show_bug.cgi?id=135497

Reviewed by Gyuyoung Kim.

* PlatformEfl.cmake: Removed ewk_defins.h from the installation list.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@171910 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Select popup is not relaunched on the EFL port

@hotfix

Related bug : https://bugs.webkit.org/show_bug.cgi?id=135454