gentoo: be more verbose

gentoo

@@ -4,7 +4,7 @@ FROM gentoo/stage3:latest
 COPY --from=portage /var/db/repos/gentoo /var/db/repos/gentoo
 
 ENV ACCEPT_KEYWORDS="amd64" \
-    EMERGE_DEFAULT_OPTS="--jobs=9 --load-average=8 --with-bdeps=y" \
+    EMERGE_DEFAULT_OPTS="--jobs=9 --load-average=8 --with-bdeps=y --verbose" \
     FEATURES="-sandbox -usersandbox -ipc-sandbox -mount-sandbox -network-sandbox -pid-sandbox" \
     MAKEOPTS="-j9 -l8" \
     USE="cairo introspection jpeg tiff"