mariadb: new package

MariaDB is a drop-in replacement for MySQL. This commit adds a current
and stable version of MariaDB to the tree.

Quite a few ideas/patches were copied from Alpine Linux, Busybox Buildroot
and Debian.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

utils/mariadb/patches/110-pcre.cmake.patch

@@ -0,0 +1,11 @@
+--- a/cmake/pcre.cmake
++++ b/cmake/pcre.cmake
+@@ -14,6 +14,8 @@ MACRO (CHECK_PCRE)
+         return -pcre_exec(NULL, NULL, NULL, -999, -999, 0, NULL, 0) < 256;
+         }"  PCRE_STACK_SIZE_OK)
+       SET(CMAKE_REQUIRED_LIBRARIES)
++    ELSE()
++      SET(PCRE_STACK_SIZE_OK TRUE)
+     ENDIF()
+   ENDIF()
+   IF(NOT HAVE_PCRE_STACK_GUARD OR NOT PCRE_STACK_SIZE_OK OR