Replace bit-position with bitvector-position

The old name was wonky and had bad argument order.

* NEWS: Add entry.
* doc/ref/api-data.texi (Bit Vectors): Update.
* libguile/bitvectors.h:
* libguile/bitvectors.c (scm_bitvector_position): New function.
* libguile/deprecated.h:
* libguile/deprecated.c (scm_bit_position): Deprecate.
* module/ice-9/sandbox.scm (bitvector-bindings): Replace bit-position
  with bitvector-position.
* module/language/cps/intset.scm (bitvector->intset): Use
  bitvector-position.
* module/system/vm/frame.scm (available-bindings): Use
  bitvector-position.
* test-suite/tests/bitvectors.test ("bitvector-position"): Add test.

module/ice-9/sandbox.scm

@@ -1076,9 +1076,9 @@ allocation limit is exceeded, an exception will be thrown to the
 (define bitvector-bindings
   '(((guile)
      bitvector-count
+     bitvector-position
      bit-count*
      bit-extract
-     bit-position
      bitvector
      bitvector->list
      bitvector-length

module/language/cps/intset.scm

@@ -781,7 +781,7 @@
         out
         (intset-union out (make-intset min *leaf-bits* tail))))
   (let lp ((out empty-intset) (min 0) (pos 0) (tail 0))
-    (let ((pos (bit-position #t bv pos)))
+    (let ((pos (bitvector-position bv #t pos)))
       (cond
        ((not pos)
         (finish-tail out min tail))

module/system/vm/frame.scm

@@ -283,7 +283,7 @@
                             (bit-set*! tmp (vector-ref killv (1- n)) #f)
                             tmp))))
             (let lp ((n 0))
-              (let ((n (bit-position #t live n)))
+              (let ((n (bitvector-position live #t n)))
                 (if n
                     (match (vector-ref defs n)
                       (#(name def-offset slot representation)