only pass -DNSIS_VERSION to files that actually use it

git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@4067 212acab6-be3b-0410-9dea-997c60f758d6

Source/SConscript

@@ -72,9 +72,23 @@ conf.Finish()
 #env['PCH'] = env.PCH(pch)[0]
 #env['PCHSTOP'] = pch
 
-##### Defines
+##### Version define
 
-env.Append(CPPDEFINES = ['NSIS_VERSION=v$NSIS_VERSION'])
+version_env = env.Copy()
+version_env.Append(CPPDEFINES = ['NSIS_VERSION=v$VERSION'])
+
+# only pass -DNSIS_VERSION to files that use it to minimize rebuilds
+
+new_makensis_files = []
+
+for file in makensis_files:
+	f = File(file).srcnode().abspath
+	if open(f).read().find('NSIS_VERSION') >= 0:
+		new_makensis_files.append(version_env.Object(file))
+	else:
+		new_makensis_files.append(file)
+
+makensis_files = new_makensis_files
 
 ##### LZMA specific defines