Add support in Weston for X cursor themes.
Add support in Weston for X cursor themes.

This patch, along with the wayland patch, adds the ability to specify
a cursor theme in the weston.ini file:

[cursors]
theme=THEME_NAME

If specified, than Weston can use a specific X cursor theme for the
pointer. This relies on the 0001-Add-support-for-X-cursor-themes.patch
for wayland.

[krh: edited to use shell section and key name cursor-theme]

sir-murray/weston,giucam/weston,Gnurou/weston,Fantu/compositor-spice,krezovic/weston,eyolfson/weston,sir-murray/weston,kwm81/weston,udoprog/weston,jonnylamb/weston,mchalupa/weston,eyolfson/weston,Tarnyko/weston-xdg_surface_present,Gnurou/weston,xorgy/weston,mchalupa/weston,udoprog/weston,xorgy/weston,jonnylamb/weston,Tarnyko/weston-xdg_surface_present,kwm81/weston,Fantu/compositor-spice,Fantu/compositor-spice,krezovic/weston,giucam/weston