CMake: expat code in separate file

Consistent with other external libraries.

build/cmake/lib/CMakeLists.txt

@@ -20,7 +20,7 @@ if(wxBUILD_MONOLITHIC)
 endif()
 
 # Define third party libraries
-set(LIBS_THIRDPARTY regex zlib)
+set(LIBS_THIRDPARTY regex zlib expat)
 if(wxUSE_GUI)
     list(APPEND LIBS_THIRDPARTY jpeg png tiff)
 endif()

build/cmake/lib/expat.cmake

@@ -0,0 +1,22 @@
+#############################################################################
+# Name:        build/cmake/lib/expat.cmake
+# Purpose:     Use external or internal expat lib
+# Author:      Tobias Taschner
+# Created:     2016-09-21
+# Copyright:   (c) 2016 wxWidgets development team
+# Licence:     wxWindows licence
+#############################################################################
+
+wx_add_thirdparty_library(wxUSE_EXPAT EXPAT "use expat for XML parsing" DEFAULT_APPLE sys)
+
+if(wxUSE_EXPAT STREQUAL "builtin")
+    wx_add_builtin_library(wxexpat
+        src/expat/expat/lib/xmlparse.c
+        src/expat/expat/lib/xmlrole.c
+        src/expat/expat/lib/xmltok.c
+    )
+    set(EXPAT_LIBRARIES wxexpat)
+    set(EXPAT_INCLUDE_DIRS ${wxSOURCE_DIR}/src/expat/expat/lib)
+elseif(wxUSE_EXPAT)
+    find_package(EXPAT REQUIRED)
+endif()

build/cmake/lib/xml/CMakeLists.txt

@@ -9,18 +9,6 @@
 
 include(../../source_groups.cmake)
 
-if(wxUSE_EXPAT STREQUAL "builtin")
-    wx_add_builtin_library(wxexpat
-        src/expat/expat/lib/xmlparse.c
-        src/expat/expat/lib/xmlrole.c
-        src/expat/expat/lib/xmltok.c
-    )
-    set(EXPAT_LIBRARIES wxexpat)
-    set(EXPAT_INCLUDE_DIRS ${wxSOURCE_DIR}/src/expat/expat/lib)
-elseif(wxUSE_EXPAT)
-    find_package(EXPAT)
-endif()
-
 wx_append_sources(XML_FILES XML)
 wx_add_library(xml IS_BASE ${XML_FILES})
 wx_lib_link_libraries(xml

build/cmake/options.cmake

@@ -56,8 +56,6 @@ wx_option(wxUSE_VISIBILITY "use of ELF symbols visibility")
 # ---------------------------------------------------------------------------
 # external libraries
 # ---------------------------------------------------------------------------
-wx_add_thirdparty_library(wxUSE_EXPAT EXPAT "use expat for XML parsing"
-    DEFAULT_APPLE sys)
 
 wx_option(wxUSE_OPENGL "use OpenGL (or Mesa)")