improve match code generation

no need for the ## predicates, plus the compiler understands the
regular ones.

src/gerbil/core/match.ss

@@ -294,7 +294,7 @@ package: gerbil/core
           ((cons: hd tl)
            (with-syntax (($hd (genident 'hd))
                          ($tl (genident 'tl)))
-             ['if #'(##pair? target)
+             ['if #'(pair? target)
                (let ((hd-pat (stx-e #'hd))
                      (tl-pat (stx-e #'tl)))
                  (cond
@@ -315,12 +315,12 @@ package: gerbil/core
                                 E)])))
                E]))
           ((null:)
-           ['if #'(##null? target) K E])
+           ['if #'(null? target) K E])
           ((splice: hd rest)
            (generate-splice tgt #'hd #'rest K E))
           ((box: pat)
            (with-syntax (($tgt (genident 'e)))
-             ['if #'(##box? target)
+             ['if #'(box? target)
                ['let #'(($tgt (##unbox target)))
                  (generate1 #'$tgt #'pat K E)]
                E]))
@@ -337,13 +337,13 @@ package: gerbil/core
            (syntax-case #'body ()
              ((simple: body)
               (with-syntax ((len (stx-length #'body)))
-                ['if #'(##vector? target)
+                ['if #'(vector? target)
                   ['if #'(##fx= (##vector-length target) len)
                     (generate-simple-vector tgt #'body 0 K E)
                     E]
                   E]))
              ((list: body)
-              ['if #'(##vector? target)
+              ['if #'(vector? target)
                 (generate-list-vector tgt #'body 'vector->list K E)
                 E])))
           ((struct: info body)