Add staticlibs option in PKGBUILD

This option helps to removes static library files in packages.

Related to the thread:
https://mailman.archlinux.org/pipermail/arch-dev-public/2013-March/024552.html

Signed-off-by: Sébastien Luttringer <seblu@seblu.net>
makepkg: Use find -delete instead of -exec rm

This will save us some fork.

Reported-by: Dave Reisner <dreisner@archlinux.org>
Signed-off-by: Sébastien Luttringer <seblu@seblu.net>