package/mariadb: bump version to 10.3.10

package/mariadb: bump version to 10.3.10

Release notes:
https://mariadb.com/kb/en/library/mariadb-10310-release-notes/

Changelog: https://mariadb.com/kb/en/mariadb-10310-changelog/

This bump also fixes broken atomic support for
BR2_TOOLCHAIN_HAS_LIBATOMIC=y with mariadb-10.2:

[ 59%] Linking CXX executable mariabackup
../../storage/innobase/libinnobase.a(handler0alter.cc.o): In function `my_atomic_add64':
/home/bernd/buildroot/output/build/mariadb-10.2.17/include/my_atomic.h:274:
 undefined reference to `__sync_fetch_and_add_8'

with this defconfig

BR2_arcle=y
BR2_archs38=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM=y
BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y
BR2_TOOLCHAIN_EXTERNAL_URL="http://autobuild.buildroot.org/toolchains/tarballs/br-arcle-hs38-full-2018.02-926-gb393c24.tar.bz2"
BR2_TOOLCHAIN_EXTERNAL_GCC_7=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_4_1=y
BR2_TOOLCHAIN_EXTERNAL_LOCALE=y
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_PACKAGE_MYSQL=y
BR2_PACKAGE_MARIADB=y
BR2_PACKAGE_MARIADB_SERVER=y

Adding "-latomic" to CXXFLAGS and/or adding -DHAVE_GCC_ATOMIC_BUILTINS=1
to CONF_OPTS, like we do for mariadb-10.3, does not fix the build error
with mariadb-10.2. There the build would stop even earlier without these
options:

/home/bernd/buildroot/output/build/mariadb-10.2.17/include/my_atomic.h:138:2:
 error: #error atomic ops for this platform are not implemented
 #error atomic ops for this platform are not implemented

Mariadb-10.3 contains improved atomic support, this build error does
not occur here.

Updated license hash of README.md after upstream commits:
https://github.com/MariaDB/server/commits/10.3/README.md

my-small.cnf.sh is not provided anymore by upstream:
https://github.com/MariaDB/server/commit/7fee164faf8fce7be4ebe322d2178efd3d075eae

[Peter Seiderer: bumped to version 10.3.7]
Signed-off-by: Peter Seiderer <ps.report@gmx.net>
[Bernd: bumped to version 10.3.10, fixed atomic support,
 fixed my-small.cnf.sh, updated license hash]
Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>