Update Package.swift to remove warnings in xcode

There are several unused files for the Xcode solution and Xcode is complaining about them. I've expanded the list of excluded items to silence the "unused" warnings

Package.swift

@@ -44,6 +44,48 @@ let package = Package(
  "libwebp/webp_js",
  "libwebp/extras",
  "libwebp/imageio",
+ "libwebp/src/Makefile.am",
+ "libwebp/src/dec/Makefile.am",
+ "libwebp/src/demux/libwebpdemux.rc",
+ "libwebp/src/demux/libwebpdemux.pc.in",
+ "libwebp/src/demux/Makefile.am",
+ "libwebp/src/dsp/Makefile.am",
+ "libwebp/src/enc/Makefile.am",
+ "libwebp/src/libwebp.pc.in",
+ "libwebp/src/libwebp.rc",
+ "libwebp/src/libwebpdecoder.pc.in",
+ "libwebp/src/libwebpdecoder.rc",
+ "libwebp/src/mux/libwebpmux.pc.in",
+ "libwebp/src/mux/libwebpmux.rc",
+ "libwebp/src/mux/Makefile.am",
+ "libwebp/src/utils/Makefile.am",
+ "libwebp/ChangeLog",
+ "libwebp/doc/README",
+ "libwebp/doc/template.html",
+ "libwebp/doc/TODO",
+ "libwebp/doc/webp-container-spec.txt",
+ "libwebp/doc/webp-lossless-bitstream-spec.txt",
+ "libwebp/Makefile.am",
+ "libwebp/makefile.unix",
+ "libwebp/m4/ax_pthread.m4",
+ "libwebp/PATENTS",
+ "libwebp/README.mux",
+ "libwebp/codereview.settings",
+ "libwebp/gradlew.bat",
+ "libwebp/configure.ac",
+ "libwebp/AUTHORS",
+ "libwebp/README",
+ "libwebp/gradlew",
+ "libwebp/autogen.sh",
+ "libwebp/Makefile.vc",
+ "libwebp/gradle.properties",
+ "libwebp/NEWS",
+ "libwebp/Android.mk",
+ "libwebp/COPYING",
+ "libwebp/build.gradle",
+ "libwebp/iosbuild.sh",
+ "libwebp/CMakeLists.txt",
+ "libwebp/README.webp_js",
  ],
  publicHeadersPath: "WebP",
  cSettings: [
@@ -56,4 +98,4 @@ let package = Package(
  ]
  ),
  ]
-)
+)