Buildsystem: Clean up the revision.h target generation

- rename src/revision.h folder to src/genrev
- ensure BUILDDIR/revision.h file is cleared/removed before generation (deleted/recreated during buildmode-changes)
Note: This needs further testing, so please give feedback.

--HG--
branch : trunk
rename : src/revision.h/CMakeLists.txt => src/genrev/CMakeLists.txt

src/genrev/CMakeLists.txt

@@ -0,0 +1,16 @@
+# Copyright (C) 2008-2010 Trinity <http://www.trinitycore.org/>
+#
+# This file is free software; as a special exception the author gives
+# unlimited permission to copy and/or distribute it, with or without
+# modifications, as long as this notice is preserved.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+# Need to pass old ${CMAKE_BINARY_DIR} as param because its different at build stage
+add_custom_target(revision.h ALL
+  COMMAND ${CMAKE_COMMAND} -E remove ${CMAKE_BINARY_DIR}/revision.h
+  COMMAND ${CMAKE_COMMAND} -DBUILDDIR=${CMAKE_BINARY_DIR} -P ${CMAKE_SOURCE_DIR}/cmake/genrev.cmake
+  WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+)