qemu: Update CFLAGS and LDFLAGS overrides

QEMU used to honor LDFLAGS and CFLAGS and has since moved to accepting
them via --extra-cflags and --extra-ldflags options to configure.

source-builder/config/qemu-common-2.cfg

@@ -119,12 +119,12 @@ URL: 	   http://www.qemu.org/
   PKG_CONFIG_PATH=$SYSROOT/lib/pkgconfig \
   PKG_CONFIG_BUILD_TOP_DIR=$SB_TMPROOT \
   %{_ld_library_path}=$SYSROOT/lib \
-  LDFLAGS="-Wl,-rpath -Wl,/$SB_PREFIX_CLEAN/lib -L$SYSROOT/lib ${VDE_LDFLAGS}" \
-  CFLAGS="${CFLAGS} ${VDE_CFLAGS}" \
   ../${source_dir_qemu}/configure \
     --prefix=%{_prefix} \
     ${CROSS_PREFIX_OPTION} \
     --make=%{__make} \
+    --extra-ldflags="-Wl,-rpath -Wl,/$SB_PREFIX_CLEAN/lib -L$SYSROOT/lib ${VDE_LDFLAGS}" \
+    --extra-cflags="${CFLAGS} ${VDE_CFLAGS}" \
     %{qemu_target_list} \
     ${VDE_CONFIG} \
     %{qemu_disables}