gnu: curlftpfs: Add patches to fix bugs.

* gnu/packages/file-systems.scm (curlftpfs)[source]: Add patches.
* gnu/packages/patches/curlftpfs-fix-error-closing-file.patch,
gnu/packages/patches/curlftpfs-fix-file-names.patch,
gnu/packages/patches/curlftpfs-fix-memory-leak.patch,
gnu/packages/patches/curlftpfs-fix-no_verify_hostname.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.

gnu/packages/patches/curlftpfs-fix-no_verify_hostname.patch

@@ -0,0 +1,27 @@
+From b2ae7a152921bf36a39f01de43769ee90cbbd253 Mon Sep 17 00:00:00 2001
+From: Joseph Lansdowne <j49137@gmail.com>
+Date: Tue, 9 Apr 2019 21:08:32 +0100
+Subject: [PATCH] fix option `no_verify_hostname`
+
+Broke with a curl upgrade at some point.  1 is no longer a valid option
+- not sure exactly what it used to do.
+---
+ ChangeLog | 3 +++
+ ftpfs.c   | 4 +---
+ 2 files changed, 4 insertions(+), 3 deletions(-)
+
+diff --git a/ftpfs.c b/ftpfs.c
+index 020e559..207d5fd 100644
+--- a/ftpfs.c
++++ b/ftpfs.c
+@@ -1627,9 +1627,7 @@ static void set_common_curl_stuff(CURL* easy) {
+   }
+ 
+   if (ftpfs.no_verify_hostname) {
+-    /* The default is 2 which verifies even the host string. This sets to 1
+-     * which means verify the host but not the string. */
+-    curl_easy_setopt_or_die(easy, CURLOPT_SSL_VERIFYHOST, 1);
++    curl_easy_setopt_or_die(easy, CURLOPT_SSL_VERIFYHOST, 0);
+   }
+ 
+   curl_easy_setopt_or_die(easy, CURLOPT_INTERFACE, ftpfs.interface);