Made scons recipe regenerate revision.hpp only if svn revision changes.

SConstruct

@@ -403,8 +403,8 @@ def InstallFilteredHook(target, source, env):
                     command = command % ("50%", source, target)
              if env["verbose"]:
                 print command
-                call(Split(command))
-                return None
+             call(Split(command))
+             return None
         # Just copy non-images, and images if tinygui is off
         if env["verbose"]:
              print "cp %s %s" % (str(source), target)

src/SConscript

@@ -273,12 +273,11 @@ test_env.Program("test", test_sources + [libwesnoth_core, libwesnoth],
 
 if env["svnrev"] != "" and env["svnrev"] != "exported":
     revision_define = "#define REVISION \"%s\"\n" % env["svnrev"]
-    r = env.Command("revision.hpp", [], Action(
+    env.Command("revision.hpp", Value(env["svnrev"]), Action(
                     lambda target, source, env: open(str(target[0]), "w").write(revision_define),
                     "Generating revision.hpp..."
                     ))
     env.Append(CPPDEFINES = 'HAVE_REVISION')
-    env.AlwaysBuild(r)
 
 #
 # File inventory, for archive makes abd analysis tools