[CMake fixes] Linux X11 pixel format and Windows compilation fix

cmake/CMakeLists.txt

 # Boilerplate.
 cmake_minimum_required (VERSION 3.1)   # First version with CMAKE_CXX_STANDARD.
 project (skimake)
 set (CMAKE_CXX_STANDARD 11)
 
 # Default to Release mode.  We're mainly targeting Skia users, not Skia developers.
 if (NOT CMAKE_BUILD_TYPE)
     set (CMAKE_BUILD_TYPE Release)
 endif ()
 
@@ skipping 274 matching lines @@
 file(GLOB c_headers "../include/c/*.h")
 install(FILES ${c_headers} DESTINATION include)
 install(TARGETS skia DESTINATION lib)
 
 # SkUserConfig.h
 if (CMAKE_BUILD_TYPE STREQUAL Release)
     set (SK_RELEASE 1)
 else()
     set (SK_RELEASE 0)
 endif()
+if (UNIX AND NOT APPLE)
+  set (SK_SAMPLES_FOR_X 1)
+else()
+  set (SK_SAMPLES_FOR_X 0)
+endif()
 configure_file ("SkUserConfig.h.in" "${userconfig_directory}/SkUserConfig.h")
 
 # skia_link_arguments.txt
 set (link_arguments ${CMAKE_BINARY_DIR}/skia_link_arguments.txt)
 file (WRITE ${link_arguments} "-L${CMAKE_BINARY_DIR}\n")
 file (APPEND ${link_arguments} "-lskia\n")
 file (APPEND ${link_arguments} "-Wl,-rpath,${CMAKE_BINARY_DIR}\n")
 
 # skia_compile_arguments.txt
 set (compile_arguments ${CMAKE_BINARY_DIR}/skia_compile_arguments.txt)
@@ skipping 25 matching lines @@
         file (APPEND ${skia_h_path} "#include \"${filename_component}\"\n")
       endif ()
     endforeach()
   endif()
 endforeach()
 file(APPEND ${skia_h_path} "\n#endif  // skia_DEFINED\n")
 
 # Now build a simple example app that uses Skia via libskia.so.
 add_executable(example example.cpp)
 target_link_libraries(example skia ${OPENGL_LIBRARIES})