gnu: guile-git: Patch to support latest libgit2.

* gnu/packages/patches/guile-git-adjust-for-libgit2-1.2.0.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/guile.scm (guile-git)[source]: Use it.

gnu/local.mk

@@ -1204,6 +1204,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/guile-3.0-linux-syscalls.patch		\
   %D%/packages/patches/guile-fibers-destroy-peer-schedulers.patch \
   %D%/packages/patches/guile-gdbm-ffi-support-gdbm-1.14.patch	\
+  %D%/packages/patches/guile-git-adjust-for-libgit2-1.2.0.patch \
   %D%/packages/patches/guile-present-coding.patch		\
   %D%/packages/patches/guile-rsvg-pkgconfig.patch		\
   %D%/packages/patches/guile-emacs-fix-configure.patch		\

gnu/packages/guile.scm

@@ -792,7 +792,9 @@ (define-public guile-git
               (file-name (git-file-name name version))
               (sha256
                (base32
-                "11a51acibwi2hpaygmrpn6nwbr4lqalc87ihrgj3mhz6swbsk9n7"))))
+                "11a51acibwi2hpaygmrpn6nwbr4lqalc87ihrgj3mhz6swbsk9n7"))
+              (patches (search-patches
+                        "guile-git-adjust-for-libgit2-1.2.0.patch"))))
     (build-system gnu-build-system)
     (arguments
      `(#:make-flags '("GUILE_AUTO_COMPILE=0")))     ; to prevent guild warnings

gnu/packages/patches/guile-git-adjust-for-libgit2-1.2.0.patch

@@ -0,0 +1,78 @@
+diff --git a/configure.ac b/configure.ac
+index 107e6ca..20e9019 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -2,6 +2,7 @@ dnl Guile-Git --- GNU Guile bindings of libgit2
+ dnl Copyright © 2016-2018 Erik Edrosa <erik.edrosa@gmail.com>
+ dnl Copyright © 2017, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+ dnl Copyright © 2019 Mathieu Othacehe <m.othacehe@gmail.com>
++dnl Copyright © 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
+ dnl
+ dnl This file is part of Guile-Git.
+ dnl
+@@ -43,15 +44,20 @@ AS_IF([test "x$LIBGIT2_LIBDIR" = "x"], [
+ ])
+ AC_SUBST([LIBGIT2_LIBDIR])
+ 
++dnl Does the 'git_remote_callbacks' struct have a 'remote_ready' field?
++dnl It was added in 1.2.0, obsoleting 'resolve_url'.
++AC_CHECK_MEMBER([git_remote_callbacks.remote_ready],
++  [HAVE_REMOTE_CALLBACKS_REMOTE_READY="#true"],
++  [HAVE_REMOTE_CALLBACKS_REMOTE_READY="#false"],
++  [[#include <git2.h>]])
++AC_SUBST([HAVE_REMOTE_CALLBACKS_REMOTE_READY])
++
+ dnl Does the 'git_remote_callbacks' struct have a 'resolve_url' field?
+ dnl It's missing in libgit2 0.28.5, added in 1.0.
+-AC_CHECK_MEMBER([git_remote_callbacks.resolve_url], [], [],
++AC_CHECK_MEMBER([git_remote_callbacks.resolve_url],
++  [HAVE_REMOTE_CALLBACKS_RESOLVE_URL="#true"],
++  [HAVE_REMOTE_CALLBACKS_RESOLVE_URL="#false"],
+   [[#include <git2.h>]])
+-if test "x$ac_cv_member_git_remote_callbacks_resolve_url" = "xyes"; then
+-  HAVE_REMOTE_CALLBACKS_RESOLVE_URL="#true"
+-else
+-  HAVE_REMOTE_CALLBACKS_RESOLVE_URL="#false"
+-fi
+ AC_SUBST([HAVE_REMOTE_CALLBACKS_RESOLVE_URL])
+ 
+ dnl Those binaries are required for ssh authentication tests.
+diff --git a/git/configuration.scm.in b/git/configuration.scm.in
+index c45f698..64c4360 100644
+--- a/git/configuration.scm.in
++++ b/git/configuration.scm.in
+@@ -19,11 +19,17 @@
+ 
+ (define-module (git configuration)
+   #:export (%libgit2
++            %have-remote-callbacks-remote-ready?
+             %have-remote-callbacks-resolve-url?))
+ 
+ (define %libgit2
+   "@LIBGIT2_LIBDIR@/libgit2")
+ 
++(define %have-remote-callbacks-remote-ready?
++  ;; True if the 'git_remote_callbacks' struct has a
++  ;; 'remote_ready' field.
++  @HAVE_REMOTE_CALLBACKS_REMOTE_READY@)
++
+ (define %have-remote-callbacks-resolve-url?
+   ;; True if the 'git_remote_callbacks' struct has a 'resolve_url' field.
+   @HAVE_REMOTE_CALLBACKS_RESOLVE_URL@)
+diff --git a/git/structs.scm b/git/structs.scm
+index ca51728..be3d050 100644
+--- a/git/structs.scm
++++ b/git/structs.scm
+@@ -637,6 +637,12 @@ type to 'specified for this to take effect."
+                (push-update-reference ,(bs:pointer uint8))
+                (push-negotiation ,(bs:pointer uint8))
+                (transport ,(bs:pointer uint8))
++
++               ;; Added in libgit2 1.2.0.
++               ,@(if %have-remote-callbacks-remote-ready?
++                     `((remote-ready ,(bs:pointer uint8)))
++                     '())
++
+                (payload ,(bs:pointer uint8))
+ 
+                ;; libgit2 1.0 added this field, which is missing from 0.28.5,