Fix AIDL syntax

Since syntax/java.vim was removed, we base the syntax highlighting on
the Vim's builtin syntax/java.vim.

syntax/aidl.vim

@@ -13,15 +13,14 @@ if exists("b:current_syntax")
   finish
 endif
 
-source <sfile>:p:h/java.vim
+if filereadable($VIMRUNTIME . "/syntax/java.vim")
+  source $VIMRUNTIME/syntax/java.vim
+endif
 
-syn keyword aidlParamDir in out inout
+syn keyword aidlStorageClass in out inout const oneway
-syn keyword aidlKeyword const oneway parcelable
+syn keyword aidlInterfaceDecl parcelable union
 
-" Needed for the 'in', 'out', 'inout' keywords to be highlighted.
+hi def link aidlStorageClass javaStorageClass
-syn cluster javaTop add=aidlParamDir
+hi def link aidlInterfaceDecl javaClassDecl
-
-hi def link aidlParamDir StorageClass
-hi def link aidlKeyword Keyword
 
 let b:current_syntax = "aidl"