[io2d]Fix linux build: add dependency cairo[x11].

ports/io2d/CONTROL

@@ -1,4 +1,4 @@
 Source: io2d
-Version: 2019-07-11
+Version: 2019-07-11-1
 Description: a lightweight, cross platform drawing library
-Build-Depends: cairo (!osx), graphicsmagick (!osx)
+Build-Depends: cairo (!osx), cairo[x11] (linux), graphicsmagick (!osx)

ports/io2d/fix-linux-build.patch

@@ -0,0 +1,22 @@
+diff --git a/P0267_RefImpl/P0267_RefImpl/cairo/CMakeLists.txt b/P0267_RefImpl/P0267_RefImpl/cairo/CMakeLists.txt
+index 5ebeb6a..d0e9176 100644
+--- a/P0267_RefImpl/P0267_RefImpl/cairo/CMakeLists.txt
++++ b/P0267_RefImpl/P0267_RefImpl/cairo/CMakeLists.txt
+@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.8)
+ project(io2d CXX)
+
+ find_package(Cairo REQUIRED)
+-find_package(GraphicsMagick REQUIRED)
++find_package(unofficial-graphicsmagick REQUIRED)
+
+ add_library(io2d_cairo
+ 	cairo_renderer-graphicsmagickinit.cpp
+@@ -24,7 +24,7 @@ target_include_directories(io2d_cairo PUBLIC
+
+ target_compile_features(io2d_cairo PUBLIC cxx_std_17)
+
+-target_link_libraries(io2d_cairo PUBLIC io2d_core Cairo::Cairo GraphicsMagick::GraphicsMagick)
++target_link_libraries(io2d_cairo PUBLIC io2d_core Cairo::Cairo unofficial::graphicsmagick::graphicsmagick)
+
+ install(
+ 	TARGETS io2d_cairo EXPORT io2d_targets

ports/io2d/portfile.cmake

@@ -11,7 +11,9 @@ vcpkg_from_github(
     REF add3c9792dcd3f08c497ae3adafb2a3b5b5fc338
     SHA512 2727342fbb31523583374ab6df6ff7542e80b4f94319cf0f293e8c085711fa10ed312b4fc4b91391112b5e27eaaae519cb4141ea9d4108ffb5b7383a043b38b8
     HEAD_REF master
-    PATCHES find-package.patch
+    PATCHES
+        find-package.patch
+        fix-linux-build.patch
 )
 
 # Configure the library, using CMake