Update gitignore

.gitignore

@@ -1,16 +1,10 @@
 # mac related files
 .DS_Store
-mac/Intermediate Build Files
-common/build/SuperCollider.app
-common/build/SuperColliderAU.component
-common/build/libscsynth.a
-common/build/plugins
-common/build/sclang
-common/build/scsynth
-common/build/*.app/
-mac/*.xcodeproj/*.mode1
-mac/*.xcodeproj/*.pbxuser
-mac/*.xcodeproj/*.mode1v3
+platform/mac/Intermediate Build Files
+platform/mac/*.xcodeproj/*.mode1
+platform/mac/*.xcodeproj/*.pbxuser
+platform/mac/*.xcodeproj/*.mode1v3
+platform/mac/build
 
 # scons specific files
 config.log