[fix] compilers: derived compiler should also handle syntax options.

Makefile

@@ -208,7 +208,7 @@ install-qmlflat: # depends on opabsl_for_compiler, but we don't want to run ocam
 	@echo "set -e" >> $(INSTALL_DIR)/bin/qmlflat
 	@echo "set -u" >> $(INSTALL_DIR)/bin/qmlflat
 	@chmod 755 $(INSTALL_DIR)/bin/qmlflat
-	@echo 'exec opa --no-stdlib --no-server --no-cps --no-closure --no-ei --no-constant-sharing --no-undot --separated off --value-restriction disabled --no-warn duplicateL0  --no-warn typer.warncoerce --no-warn unused --no-discard-of-unused-stdlib --no-warn pattern $$(if ! grep -qE "(^| )--no-stdlib( |$$)" <<<"$$*"; then echo $(shell sed "s%^[^# ]\+%$(PREFIX)/share/opa/mlstatebsl/opabslgen_&%; t OK; d; :OK" opabsl/mlstatebsl/bsl-sources); fi) "$$@"' \
+	@echo 'exec opa --parser classic --no-stdlib --no-server --no-cps --no-closure --no-ei --no-constant-sharing --no-undot --separated off --value-restriction disabled --no-warn duplicateL0  --no-warn typer.warncoerce --no-warn unused --no-discard-of-unused-stdlib --no-warn pattern $$(if ! grep -qE "(^| )--no-stdlib( |$$)" <<<"$$*"; then echo $(shell sed "s%^[^# ]\+%$(PREFIX)/share/opa/mlstatebsl/opabslgen_&%; t OK; d; :OK" opabsl/mlstatebsl/bsl-sources); fi) "$$@"' \
 	>> $(INSTALL_DIR)/bin/qmlflat
 
 # installs some dev tools on top of the normal install; these should not change often

libruntime/serverArg.ml

@@ -378,6 +378,7 @@ let import_arg_spec = function
   | A.Set_int r -> !> int (fun i -> r := i)
   | A.Float f -> !> float f
   | A.Set_float r -> !> float (fun f -> r := f)
+  | A.Symbol (_l, f) -> !> string f
 
   (* The rest is not implemented, you can add it if you need *)
   | _ -> assert false

opatop/opaTopMain.ml

@@ -208,6 +208,7 @@ let spec = [
   @ ( Sa.import_arg_options OManager.Arg.options )
   @ ( Sa.import_arg_options [OManager.Arg.version "opatop"] )
   @ ( Sa.import_arg_options WarningClass.Arg.options )
+  @ ( Sa.import_arg_options OpaSyntax.Args.options )
 
 (**
    Anon function for non --option arguments

qml2js/qml2jsOptions.ml

@@ -247,6 +247,7 @@ struct
     @ PassHandler.Arg.options
     @ WarningClass.Arg.options
     @ Qml2jsBackendOptions.Arg.options
+    @ OpaSyntax.Args.options
 
   let speclist () =
     Arg.sort