This gets rid of the horrible hack in gbuild.mk to accomodate the
case-incorrect iOS platform makefiles that cannot be renamed without
upsetting git on file systems that sadly lack the case sensitivity
feature.

Keep the macro defined to IOS though.

Change-Id: I1022bfef4900da00e75fc1ccce786b20f8673234
Reviewed-on: https://gerrit.libreoffice.org/62705
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>
Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Tor Lillqvist <tml@collabora.com>