package/pkgconf: purge trailing '/' from PKGCONF_SITE
<PKG>_SITE cannot have a trailing slash.
This was not detected by the check in generic-package because it is a
host-only package without Config.in symbol.
Signed-off-by: Carlos Santos <casantos@datacom.com.br>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Carlos Santos