Fixed build & install. Added mux library.

ports/libwebp/CONTROL

@@ -1,3 +1,3 @@
 Source: libwebp
-Version: 0.6.1
+Version: 0.6.1-1
 Description: Lossy compression of digital photographic images.

ports/libwebp/build_fixes.patch

@@ -0,0 +1,33 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 3b105e37..f9b806c4 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -106,6 +106,9 @@ endforeach()
+ if(MSVC)
+   # avoid security warnings for e.g., fopen() used in the examples.
+   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
++  if(BUILD_SHARED_LIBS)
++    add_definitions(-DWEBP_EXTERN=__declspec\(dllexport\))
++  endif()
+ else()
+   add_definitions(-Wall)
+ endif()
+@@ -235,6 +238,10 @@ if(WEBP_BUILD_GIF2WEBP AND NOT GIF_FOUND)
+ endif()
+ 
+ if(WEBP_BUILD_GIF2WEBP OR WEBP_BUILD_IMG2WEBP)
++  set(WEBP_BUILD_MUX ON)
++endif()
++
++if(WEBP_BUILD_MUX)
+   parse_Makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/src/mux "WEBP_MUX_SRCS"
+     "")
+   add_library(webpmux ${WEBP_MUX_SRCS})
+@@ -322,6 +329,7 @@ install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/src/webp/decode.h
+               ${CMAKE_CURRENT_SOURCE_DIR}/src/webp/types.h
+         DESTINATION include/webp)
+ install(TARGETS ${INSTALLED_LIBRARIES}
++        RUNTIME DESTINATION bin
+         LIBRARY DESTINATION lib
+         ARCHIVE DESTINATION lib)
+ 

ports/libwebp/portfile.cmake

@@ -11,15 +11,20 @@ vcpkg_download_distfile(ARCHIVE
 )
 vcpkg_extract_source_archive(${ARCHIVE})
 
+vcpkg_apply_patches(
+    SOURCE_PATH ${SOURCE_PATH}
+    PATCHES
+        ${CMAKE_CURRENT_LIST_DIR}/build_fixes.patch
+)
+
 vcpkg_configure_cmake(
     SOURCE_PATH ${SOURCE_PATH}
     PREFER_NINJA
-    # dllexport support seem to be broken
-    OPTIONS -DCMAKE_WINDOWS_EXPORT_ALL_SYMBOLS=ON
+    OPTIONS
         -DCMAKE_DEBUG_POSTFIX=d
+        -DWEBP_BUILD_MUX=ON
 )
 
-vcpkg_build_cmake()
 vcpkg_install_cmake()
 
 file(REMOVE_RECURSE ${CURRENT_PACKAGES_DIR}/debug/include)