iosbuild.sh: add WebPDecoder.framework + encoder

WebPDecoder.framework replaces WebP.framework as the decode-only
framework.
WebP.framework now includes the full library allowing for use of the
encoder.

BUG=webp:307

Change-Id: Ic8139f201576bf94b0d4a31cb7cad0655cd8ba97
(cherry picked from commit 1d5046d1f9a863d8a13460e5405fef8c0acd3db0)
1 file changed