1) fix rebuilding with existing staging area
2) fix dependency to libmysqlclient (fixes #3132)

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

- Add some more patches from Debian
- Rename existing ones (our own patches starts with prefix 1000+)

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

This is a copy of the existing php5 stuff, adopted for PHP7.

Please not, that its not supported to install both php5
and php7 in parallel on the target.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>