iosbuild.sh: add WebP{Demux,Mux}.framework
iosbuild.sh: add WebP{Demux,Mux}.framework

Change-Id: I2c16475a7bf9f63d07f4298df7c68859226669d5

PKRoma/libwebp,webmproject/libwebp,webmproject/libwebp,webmproject/libwebp,webmproject/libwebp,PKRoma/libwebp,PKRoma/libwebp,PKRoma/libwebp,webmproject/libwebp,PKRoma/libwebp,PKRoma/libwebp