All: Only update version info if needed

CHANGES

@@ -1,3 +1,7 @@
+0.6.0: (Future)
+Misc:
+ - All: Only update version info if needed
+
 0.5.0: (2016-09-19)
 Features:
  - Game Boy support

CMakeLists.txt

@@ -122,7 +122,7 @@ function(find_feature FEATURE_NAME FEATURE_REQUIRES)
 endfunction()
 
 # Version information
-add_custom_target(version-info ALL ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_SOURCE_DIR}/src/core/version.c.in
+add_custom_target(version-info ALL
 	COMMAND ${CMAKE_COMMAND}
 	-DBINARY_NAME=${BINARY_NAME}
 	-DCONFIG_FILE=${CMAKE_CURRENT_SOURCE_DIR}/src/core/version.c.in

version.cmake

@@ -43,6 +43,10 @@ if(NOT GIT_BRANCH)
 	set(GIT_BRANCH "(unknown)")
 endif()
 
-if(CONFIG_FILE AND OUT_FILE)
-	configure_file("${CONFIG_FILE}" "${OUT_FILE}")
+if(NOT VERSION_STRING_CACHE OR NOT VERSION_STRING STREQUAL VERSION_STRING_CACHE)
+	set(VERSION_STRING_CACHE ${VERSION_STRING} CACHE STRING "" FORCE)
+
+	if(CONFIG_FILE AND OUT_FILE)
+		configure_file("${CONFIG_FILE}" "${OUT_FILE}")
+	endif()
 endif()