gnu: mariadb: Fix CVE-2021-27928.

* gnu/packages/patches/mariadb-CVE-2021-27928.patch: New patch.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/databases.scm (mariadb/fixed): New variable. Apply patch.
(mariadb)[replacement]: Graft.

gnu/packages/databases.scm

@@ -734,6 +734,7 @@ Language.")
                             (append (find-files "extra/wolfssl")
                                     (find-files "zlib")))
                   #t))))
+    (replacement mariadb/fixed)
     (build-system cmake-build-system)
     (outputs '("out" "lib" "dev"))
     (arguments
@@ -969,6 +970,13 @@ Language.")
 as a drop-in replacement of MySQL.")
     (license license:gpl2)))
 
+(define mariadb/fixed
+  (package
+    (inherit mariadb)
+    (source (origin
+              (inherit (package-source mariadb))
+              (patches (search-patches "mariadb-CVE-2021-27928.patch"))))))
+
 (define-public mariadb-connector-c
   (package
     (name "mariadb-connector-c")