stop vendoring modules we don't need

lib/melange_compiler_libs.ml

@@ -4,23 +4,14 @@
 *)
 
 module Annot = Annot
-module Ast_helper = Ast_helper
-module Ast_iterator = Ast_iterator
-module Ast_mapper = Ast_mapper
-module Attr_helper = Attr_helper
 module Bs_clflags = Bs_clflags
 module Btype = Btype
 module Builtin_attributes = Builtin_attributes
 module Cmi_format = Cmi_format
 module Cmt_format = Cmt_format
 module Config = Config
-module Consistbl = Consistbl
 module Ctype = Ctype
 module Datarepr = Datarepr
-module Depend = Depend
-module Diffing = Diffing
-module Diffing_with_keys = Diffing_with_keys
-module Docstrings = Docstrings
 module Env = Env
 module Envaux = Envaux
 module Errortrace = Errortrace
@@ -29,23 +20,14 @@ module Includecore = Includecore
 module Includemod = Includemod
 module Includemod_errorprinter = Includemod_errorprinter
 module Lambda = Lambda
-module Lazy_backtrack = Lazy_backtrack
-module Lexer = Lexer
-module Load_path = Load_path
 module Location = Location
 module Matching = Matching
 module Misc = Misc
 module Mtype = Mtype
 module Oprint = Oprint
-module Outcometree = Outcometree
 module Parmatch = Parmatch
-module Parse = Parse
-module Parser = Parser
-module Parsetree = Parsetree
-module Path = Path
 module Patterns = Patterns
 module Persistent_env = Persistent_env
-module Pprintast = Pprintast
 module Predef = Predef
 module Primitive = Primitive
 module Printast = Printast
@@ -55,9 +37,7 @@ module Printtyp = Printtyp
 module Printtyped = Printtyped
 module Rec_check = Rec_check
 module Shape = Shape
-module Syntaxerr = Syntaxerr
 module Signature_group = Signature_group
-module Simplif = Simplif
 module Stypes = Stypes
 module Subst = Subst
 module Switch = Switch
@@ -70,7 +50,6 @@ module Translcore = Translcore
 module Translmod = Translmod
 module Translobj = Translobj
 module Translprim = Translprim
-module Type_immediacy = Type_immediacy
 module Typeclass = Typeclass
 module Typecore = Typecore
 module Typedecl = Typedecl