qemu: QEMU fix libtool usage

QEMU uses the environment variable LIBTOOL by default.  We want to ensure
we set it to the proper libtool version, instead of letting it default to
the host system version.

This corrects target building, and ensures we're linking properly for
native and nativesdk versions.

(From OE-Core rev: b91d65fc78c18948ed4ec96f34b85c431dbc3d95)

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/qemu/qemu.inc

@@ -38,6 +38,8 @@ EXTRA_OECONF_class-nativesdk = "--target-list=${@get_qemu_target_list(d)} --disa
 				--disable-curl \
 				"
 
+export LIBTOOL="${HOST_SYS}-libtool"
+
 do_configure_prepend_class-native() {
 	# Undo the -lX11 added by linker-flags.patch, don't assume that host has libX11 installed
 	sed -i 's/-lX11//g' Makefile.target