slang: clean up options and dependencies
The AC_PATH_XTRA check for X11 headers is never actually used, so patch that out
and remove the options in EXTRA_OECONF.
Move pcre/png/zlib toggles to PACKAGECONFIG, retaining the behaviour that only
PCRE is enabled by default.
Add missing libiconv dependency.
(From OE-Core rev:
3587053646c34002fa18b87834516ce27fbd0788)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
