qemu: Avoid potential build configuration contamination

Changing the gl options to qemu doesn't result in a correctly rebuilt
binary, the GL linkage can persist from a build where it was enabled
to one where it was not.

As well as clearly being incorrect and non-reproducible, this caused
some mystery failures on the autobuilder.

Cleaning ${B} at do_configure time avoids this. Most recipes
(e.g. autotools derived ones) already clean ${B} as appropriate and
avoid this issue.

(From OE-Core rev: b91b30c09ffbcd81e8dcaae832b3ae4f61046236)

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

meta/recipes-devtools/qemu/qemu.inc

@@ -95,6 +95,7 @@ do_configure_prepend_class-native() {
 do_configure() {
     ${S}/configure ${EXTRA_OECONF}
 }
+do_configure[cleandirs] += "${B}"
 
 do_install () {
 	export STRIP=""