scripts/install: new buildsystem: add support for pre_install() and post_install() hooks via package.mk

Signed-off-by: Stephan Raue <stephan@openelec.tv>
avahi: convert to new package format

Signed-off-by: Stephan Raue <stephan@openelec.tv>
mysql: update to mysql-5.1.70

Signed-off-by: Stephan Raue <stephan@openelec.tv>
mysql: update to mysql-5.6.13, add initial and optional support for mysql server - dont use it, it will be changed later\!

Signed-off-by: Stephan Raue <stephan@openelec.tv>
ncurses: install headers to $SYSROOT_PREFIX

Signed-off-by: Stephan Raue <stephan@openelec.tv>