gnu: Removed unused patch 'readline-7.0-mingw.patch'.

This patch was introduced in commit ae12d58627,
but it was never used.

See <https://bugs.gnu.org/26581> for more information.

* gnu/packages/patches/readline-7.0-mingw.patch: Delete file.
* gnu/local.mk (dist_patch_DATA): Remove it.

gnu/local.mk

@@ -1209,7 +1209,6 @@ dist_patch_DATA =						\
   %D%/packages/patches/rct-add-missing-headers.patch		\
   %D%/packages/patches/readline-link-ncurses.patch		\
   %D%/packages/patches/readline-6.2-CVE-2014-2524.patch		\
-  %D%/packages/patches/readline-7.0-mingw.patch			\
   %D%/packages/patches/reposurgeon-add-missing-docbook-files.patch	\
   %D%/packages/patches/reptyr-fix-gcc-7.patch			\
   %D%/packages/patches/ripperx-missing-file.patch		\

gnu/packages/patches/readline-7.0-mingw.patch

@@ -1,28 +0,0 @@
-Configure checks for chown; add missing shields in code.
-
-Upstream status: not yet presented upstream.
-
---- readline-7.0/histfile.c.orig	2016-12-06 20:04:10.058901731 +0100
-+++ readline-7.0/histfile.c	2016-12-06 20:05:09.220083801 +0100
-@@ -610,8 +610,10 @@
-      user is running this, it's a no-op.  If the shell is running after sudo
-      with a shared history file, we don't want to leave the history file
-      owned by root. */
-+#if HAVE_CHOWN
-   if (rv == 0 && exists)
-     r = chown (filename, finfo.st_uid, finfo.st_gid);
-+#endif
- 
-   xfree (filename);
-   FREE (tempname);
-@@ -757,8 +759,10 @@
-      user is running this, it's a no-op.  If the shell is running after sudo
-      with a shared history file, we don't want to leave the history file
-      owned by root. */
-+#if HAVE_CHOWN
-   if (rv == 0 && exists)
-     mode = chown (histname, finfo.st_uid, finfo.st_gid);
-+#endif
- 
-   FREE (histname);
-   FREE (tempname);