add `var-ref->mod-decl-insp' and switch `cur-code-insp' uses

Macros and other tools that need syntax privilege used
`(current-code-inspector)' at the module top-level to try to
capture the right code inspector at load time. It's more
consistent to instead use the enclosing module's declaration-time
inspector, and `var-ref->mod-decl-insp' provides that. The
new function works only on references to anonymous variables,
which limits access to the inspector.

The real function name is longer, of course.

original commit: 0197902309c5400d463393829a88282c627dafd2

collects/parser-tools/private-lex/stx.rkt

@@ -28,7 +28,8 @@
               ((char-range-arg #'#\1 #'here) (char->integer #\1))
               ((char-range-arg #'"1" #'here) (char->integer #\1)))
   
-  (define orig-insp (current-code-inspector))
+  (define orig-insp (variable-reference->module-declaration-inspector
+                     (#%variable-reference)))
   (define (disarm stx)
     (syntax-disarm stx orig-insp))