siteconfig: Drop siteconfig class/code/support

The siteconfig code was only used for 5 cache values. The complexity added to sstate
to support this code was considerable and the runtime much more significant than
any benefit the cache files would have added. Drop the support for this which
was only used minimally for ncurses and zlib.

(From OE-Core rev: f3766dc038f7ba9780ddaf5eb8d27385ea31d7d0)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/siteconfig.bbclass

@@ -1,39 +0,0 @@
-#
-# Copyright OpenEmbedded Contributors
-#
-# SPDX-License-Identifier: MIT
-#
-
-python siteconfig_do_siteconfig () {
-    shared_state = sstate_state_fromvars(d)
-    if shared_state['task'] != 'populate_sysroot':
-        return
-    if not os.path.isdir(os.path.join(d.getVar('FILE_DIRNAME'), 'site_config')):
-        bb.debug(1, "No site_config directory, skipping do_siteconfig")
-        return
-    sstate_install(shared_state, d)
-    bb.build.exec_func('do_siteconfig_gencache', d)
-    sstate_clean(shared_state, d)
-}
-
-EXTRASITECONFIG ?= ""
-
-siteconfig_do_siteconfig_gencache () {
-	mkdir -p ${WORKDIR}/site_config_${MACHINE}
-	gen-site-config ${FILE_DIRNAME}/site_config \
-		>${WORKDIR}/site_config_${MACHINE}/configure.ac
-	cd ${WORKDIR}/site_config_${MACHINE}
-	autoconf
-	rm -f ${BPN}_cache
-	CONFIG_SITE="" ${EXTRASITECONFIG} ./configure ${CONFIGUREOPTS} --cache-file ${BPN}_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" \
-		< ${BPN}_cache > ${BPN}_config
-	mkdir -p ${SYSROOT_DESTDIR}${datadir}/${TARGET_SYS}_config_site.d
-	cp ${BPN}_config ${SYSROOT_DESTDIR}${datadir}/${TARGET_SYS}_config_site.d
-
-}
-
-do_populate_sysroot[sstate-interceptfuncs] += "do_siteconfig "
-
-EXPORT_FUNCTIONS do_siteconfig do_siteconfig_gencache