[OE-core] siteconfig: Clear cache before rebuilding

[Richard Purdie]

This ensures consistent build results and avoids build failures when compiler flags
change for example.

Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
---
diff --git a/meta/classes/siteconfig.bbclass b/meta/classes/siteconfig.bbclass
index ccbe5b9..2de7153 100644
--- a/meta/classes/siteconfig.bbclass
+++ b/meta/classes/siteconfig.bbclass
@@ -18,6 +18,7 @@ siteconfig_do_siteconfig_gencache () {
 		>${WORKDIR}/site_config_${MACHINE}/configure.ac
 	cd ${WORKDIR}/site_config_${MACHINE}
 	autoconf
+	rm ${PN}_cache
         CONFIG_SITE="" ${EXTRASITECONFIG} ./configure ${CONFIGUREOPTS} --cache-file ${PN}_cache
 	sed -n -e "/ac_cv_c_bigendian/p" -e "/ac_cv_sizeof_/p" \
 		-e "/ac_cv_type_/p" -e "/ac_cv_header_/p" -e "/ac_cv_func_/p" \