Fix ambiguous imports.

* gnu/packages/ocaml.scm: Hide 'zip' from (srfi srfi-1).
* guix/git.scm: Select 'mkdir-p' from (guix build utils).

gnu/packages/ocaml.scm

@@ -65,7 +65,7 @@
   #:use-module (guix packages)
   #:use-module (guix svn-download)
   #:use-module (guix utils)
-  #:use-module (srfi srfi-1))
+  #:use-module ((srfi srfi-1) #:hide (zip)))
 
 ;; A shortcut for files from ocaml forge. Downloaded files are computed from
 ;; their number, not their name.

guix/git.scm

@@ -21,7 +21,7 @@
   #:use-module (git object)
   #:use-module (guix base32)
   #:use-module (guix hash)
-  #:use-module (guix build utils)
+  #:use-module ((guix build utils) #:select (mkdir-p))
   #:use-module (guix store)
   #:use-module (guix utils)
   #:use-module (rnrs bytevectors)