[PATCH] base.bbclass: Enable using 'make clean' for rebuilds

[Richard Purdie <richard.purdie@linuxfoundation.org>]

When something rebuilds say due to ${baselib} changing or some
other key variable, software is often not rebuilt due to the
fact that make detects no dependency change.

By running "make clean" when these changes occur, we can at least try
and ensure the correct rebuilds happen. We use the same checksum check as 
autotools to decide if things have changed or not.

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

diff --git a/meta/classes/base.bbclass b/meta/classes/base.bbclass
index d6a2292..52b835e 100644
--- a/meta/classes/base.bbclass
+++ b/meta/classes/base.bbclass
@@ -230,11 +230,24 @@ gdkpixbuf_complete() {
 	GDK_PIXBUF_FATAL_LOADER=1 ${STAGING_BINDIR_NATIVE}/gdk-pixbuf-query-loaders --update-cache || exit 1
 }
 
+CONFIGURESTAMPFILE = "${WORKDIR}/configure.sstate"
+
 addtask configure after do_patch
 do_configure[dirs] = "${S} ${B}"
 do_configure[deptask] = "do_populate_sysroot"
 base_do_configure() {
-	:
+	if [ -n "${CONFIGURESTAMPFILE}" -a -e "${CONFIGURESTAMPFILE}" ]; then
+		if [ "`cat ${CONFIGURESTAMPFILE}`" != "${BB_TASKHASH}" ]; then
+			cd ${B}
+			if [ -e Makefile -o -e makefile -o -e GNUmakefile ]; then
+				${MAKE} clean
+			fi
+			find ${B} -name \*.la -delete
+		fi
+	fi
+	if [ -n "${CONFIGURESTAMPFILE}" ]; then
+		echo ${BB_TASKHASH} > ${CONFIGURESTAMPFILE}
+	fi
 }
 
 addtask compile after do_configure