The siteconfig cache files in ACLOCALDIR setup by autotools.bbclass
has been dropped after switching to RSS, so change the siteconfig
search path back to SITECONFIG_SYSROOTCACHE and the parameter
name changed from aclocalcache to sysrootcache.
Signed-off-by: Jackie Huang <jackie.huang@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>