cleanup gitignore

Reviewed By: jberdine

Differential Revision: D3398534

fbshipit-source-id: 4116a91

.gitignore

@@ -35,7 +35,6 @@ _build
 /infer/tests/.idea/tasks.xml
 /infer/tests/.idea/uiDesigner.xml
 /infer/tests/.idea/workspace.xml
-/infer/tests/.idea/misc.xml
 /infer/tests/.idea/runConfigurations
 /infer/tests/.idea/copyright/profiles_settings.xml
 
@@ -90,12 +89,9 @@ buck-out/
 /infer/src/backend/jsonbug_*
 
 # intelliJ files
-.idea
-*.iml
-
 /infer/src/backend/.projectSettings
-/infer/models/out/
 
+# copied from facebook-clang-plugins or generated by atdgen
 /infer/src/clang/clang_ast_b.ml
 /infer/src/clang/clang_ast_b.mli
 /infer/src/clang/clang_ast_j.ml
@@ -109,6 +105,7 @@ buck-out/
 /infer/src/clang/clang_ast_visit.ml
 /infer/src/clang/clang_ast_main.ml
 
+# copied over by make
 /infer/src/llvm/lLexer.ml
 /infer/src/llvm/lParser.ml