libxslt: depends on libxml2, move package, convert to new package format, update to libxslt-1.1.28

Signed-off-by: Stephan Raue <stephan@openelec.tv>
libdrm: update to libdrm-2.4.50

Signed-off-by: Stephan Raue <stephan@openelec.tv>
pixman: update to pixman-0.32.4

Signed-off-by: Stephan Raue <stephan@openelec.tv>
xproto: update to xproto-7.0.25

Signed-off-by: Stephan Raue <stephan@openelec.tv>
util-macros: update to util-macros-1.18.0

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