[cmake] Avoid modifying `ftconfig.h' and `ftoption.h' files.

* CMakeLists.txt: Each time cmake is run those files are
modified and the whole FreeType library is recompiled.  With this
change we change the files only if there are real modifications, so
we can avoid recompilations.

CMakeLists.txt

@@ -215,14 +215,17 @@ if (UNIX)
   endif ()
   string(REPLACE "/undef " "#undef "
     FTCONFIG_H "${FTCONFIG_H}")
-  file(WRITE "${PROJECT_BINARY_DIR}/include/freetype/config/ftconfig.h"
+  file(WRITE "${PROJECT_BINARY_DIR}/include/freetype/config/ftconfig.h-new"
     "${FTCONFIG_H}")
 else ()
   file(READ "${PROJECT_SOURCE_DIR}/include/freetype/config/ftconfig.h"
     FTCONFIG_H)
-  file(WRITE "${PROJECT_BINARY_DIR}/include/freetype/config/ftconfig.h"
+  file(WRITE "${PROJECT_BINARY_DIR}/include/freetype/config/ftconfig.h-new"
     "${FTCONFIG_H}")
 endif ()
+execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
+  "${PROJECT_BINARY_DIR}/include/freetype/config/ftconfig.h-new"
+  "${PROJECT_BINARY_DIR}/include/freetype/config/ftconfig.h")
 
 
 # Create the options file
@@ -251,8 +254,11 @@ if (HARFBUZZ_FOUND)
     "/\\* +(#define +FT_CONFIG_OPTION_USE_HARFBUZZ) +\\*/" "\\1"
     FTOPTION_H "${FTOPTION_H}")
 endif ()
-file(WRITE "${PROJECT_BINARY_DIR}/include/freetype/config/ftoption.h"
+file(WRITE "${PROJECT_BINARY_DIR}/include/freetype/config/ftoption.h-new"
   "${FTOPTION_H}")
+execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
+  "${PROJECT_BINARY_DIR}/include/freetype/config/ftoption.h-new"
+  "${PROJECT_BINARY_DIR}/include/freetype/config/ftoption.h")
 
 
 # Specify library include directories

ChangeLog

@@ -1,3 +1,12 @@
+2016-06-09  David Capello  <davidcapello@gmail.com>
+
+	[cmake] Avoid modifying `ftconfig.h' and `ftoption.h' files.
+
+	* CMakeLists.txt: Each time cmake is run those files are
+	modified and the whole FreeType library is recompiled.  With this
+	change we change the files only if there are real modifications, so
+	we can avoid recompilations.
+
 2016-06-09  Werner Lemberg  <wl@gnu.org>
 
 	[bdf] Check number of properties (#48166).