Make iOS builders generate debug information in a separate dSYM file

Make iOS builders generate debug information in a separate dSYM file
https://bugs.webkit.org/show_bug.cgi?id=149696

Reviewed by Darin Adler.

Similar to the Mac builders, the iOS builders should write debug information
into a separate dSYM file instead of including such information in the binary
itself (default Xcode behavior)

* BuildSlaveSupport/build.webkit.org-config/master.cfg:
(CompileWebKit.start):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@190801 268f45cc-cd09-0410-ab3c-d52691b4dbfc