package/poco: bump to version 1.11.1

This commit drop patches, as they are now included upstream or no longer
needed. It also introduces a new patch to fix a build failure for nios2.

MySQL include and library paths can now be provided in variables passed
to the build command. Variables MYSQL_{INC,LIB}DIR are renamed to
POCO_MYSQL_{INCLUDE,LIB}. For PostgreSQL support, variables
POCO_PGSQL_{INCLUDE,LIB} are also passed the same way to the build
command.

This poco version 1.11.1 introduces a new ActiveRecord component.

For changelog, see:
https://raw.githubusercontent.com/pocoproject/poco/poco-1.11.1-release/CHANGELOG



Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>