Apply debian/patches/38_scripts__mysqld_safe.sh__signals.dpatch

We have carried along this patch as a patch inside our sources
since 2012 (commit cfd4fcb).

This same patch has been used also in MySQL packaging at Oracle
and in downstream Debian.org packages for both MySQL and MariaDB.

The validity of this has thus been vetted in production for years
and the review done now did not find otherwise.

Code contributed to Oracle with
http://forge.mysql.com/wiki/Sun_Contributor_Agreement

Reported as http://bugs.mysql.com/bug.php?id=31361

debian/patches/00list

@@ -1,2 +1 @@
-38_scripts__mysqld_safe.sh__signals.dpatch
 61_replace_dash_with_bash_mbug675185.dpatch

scripts/mysqld_safe.sh

@@ -36,7 +36,6 @@ skip_err_log=0
 syslog_tag_mysqld=mysqld
 syslog_tag_mysqld_safe=mysqld_safe
 
-trap '' 1 2 3 15			# we shouldn't let anyone kill us
 
 # MySQL-specific environment variable. First off, it's not really a umask,
 # it's the desired mode. Second, it follows umask(2), not umask(3) in that
@@ -160,7 +159,7 @@ eval_log_error () {
       # sed buffers output (only GNU sed supports a -u (unbuffered) option)
       # which means that messages may not get sent to syslog until the
       # mysqld process quits.
-      cmd="$cmd 2>&1 | logger -t '$syslog_tag_mysqld' -p daemon.error"
+      cmd="$cmd 2>&1 | logger -t '$syslog_tag_mysqld' -p daemon.error & wait"
       ;;
     *)
       echo "Internal program error (non-fatal):" \
@@ -877,6 +876,13 @@ then
   exit 1
 fi
 
+#
+# From now on, we catch signals to do a proper shutdown of mysqld
+# when signalled to do so.
+#
+trap '/usr/bin/mysqladmin --defaults-extra-file=/etc/mysql/debian.cnf refresh & wait' 1 # HUP
+trap '/usr/bin/mysqladmin --defaults-extra-file=/etc/mysql/debian.cnf shutdown' 2 3 15 # INT QUIT and TERM
+
 #
 # Uncomment the following lines if you want all tables to be automatically
 # checked and repaired during startup. You should add sensible key_buffer