enable JuliaSyntax parser for user code in juliac (#57777)

This was an oversight.

Author: JeffBezanson

contrib/juliac-buildscript.jl

@@ -17,6 +17,9 @@ task.rngState3 = 0x3a77f7189200c20b
 task.rngState4 = 0x5502376d099035ae
 uuid_tuple = (UInt64(0), UInt64(0))
 ccall(:jl_set_module_uuid, Cvoid, (Any, NTuple{2, UInt64}), Base.__toplevel__, uuid_tuple)
+if Base.get_bool_env("JULIA_USE_FLISP_PARSER", false) === false
+    Base.JuliaSyntax.enable_in_core!()
+end
 
 # Patch methods in Core and Base