install: Add bindir, libdir and includedir configure opts.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
loaders: gif: Fix build with giflib > 5.0.0

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
install: Fix symlink creation.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
build: Update list of exported syms.

After input drivers were moved to backends
the symbols needs to be moved too.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>