lib/portage/package/ebuild/doebuild.py: fix undefined self

Fixes: 98a8a4af2c77477c327b22621b8a0aed6d15f574
Signed-off-by: Sam James <sam@gentoo.org>
diff --git a/lib/portage/package/ebuild/doebuild.py b/lib/portage/package/ebuild/doebuild.py
index 34720c7..0ff64e2 100644
--- a/lib/portage/package/ebuild/doebuild.py
+++ b/lib/portage/package/ebuild/doebuild.py
@@ -3096,7 +3096,7 @@
             f.write(soname_deps.provides)
     else:
         if check_dyn_libs_inconsistent(image_dir, soname_deps.provides):
-            self._writemsg_level(
+            portage.util._writemsg_level(
                 colorize(
                     "BAD",
                     "!!! Error! Installing dynamic libraries (.so) with blank PROVIDES!",