Adding an option to the gf compiler to add an index to pgf files

This is gonna be used by the android library to skip unused part of a
pgf file

src/compiler/GF/Infra/Option.hs

@@ -167,6 +167,7 @@ data Flags = Flags {
       optEncoding        :: String,
       optOptimizations   :: Set Optimization,
       optOptimizePGF     :: Bool,
+      optMkIndexPGF     :: Bool,
       optCFGTransforms   :: Set CFGTransform,
       optLibraryPath     :: [FilePath],
       optStartCat        :: Maybe String,
@@ -268,6 +269,7 @@ defaultFlags = Flags {
       optEncoding        = "latin1",
       optOptimizations   = Set.fromList [OptStem,OptCSE,OptExpand,OptParametrize],
       optOptimizePGF     = False,
+      optMkIndexPGF     = False,
       optCFGTransforms   = Set.fromList [CFGRemoveCycles, CFGBottomUpFilter, 
                                          CFGTopDownFilter, CFGMergeIdentical],
       optLibraryPath     = [],
@@ -360,6 +362,8 @@ optDescr =
                 "Select an optimization package. OPT = all | values | parametrize | none",
      Option [] ["optimize-pgf"] (NoArg (optimize_pgf True))
                 "Enable or disable global grammar optimization. This could significantly reduce the size of the final PGF file",
+     Option [] ["mk-index"] (NoArg (mkIndex True))
+                "Add an index to the pgf file",
      Option [] ["stem"] (onOff (toggleOptimize OptStem) True) "Perform stem-suffix analysis (default on).",
      Option [] ["cse"] (onOff (toggleOptimize OptCSE) True) "Perform common sub-expression elimination (default on).",
      Option [] ["cfg"] (ReqArg cfgTransform "TRANS") "Enable or disable specific CFG transformations. TRANS = merge, no-merge, bottomup, no-bottomup, ...",
@@ -421,6 +425,7 @@ optDescr =
                          Nothing -> fail $ "Unknown optimization package: " ++ x
                          
        optimize_pgf x = set $ \o -> o { optOptimizePGF = x }
+       mkIndex x = set $ \o -> o { optMkIndexPGF = x }
 
        toggleOptimize x b = set $ setOptimization' x b