debian/rules: don't include buildflags.mk manually

Don't include buildflags.mk manually, debhelper >= 9 does it already,
just export the appropriate variables as specified in
https://wiki.debian.org/HardeningWalkthrough#debhelper_9

diff --git a/debian/rules b/debian/rules
index c5817c9..89ba88d 100755 (executable)
--- a/debian/rules
+++ b/debian/rules
@@ -1,9 +1,7 @@
 #!/usr/bin/make -f
 # -*- makefile -*-
 
-DEB_LDFLAGS_MAINT_APPEND=-Wl,-Bsymbolic-functions -Wl,--as-needed
-include /usr/share/dpkg/buildflags.mk
-export CFLAGS CPPFLAGS LDFLAGS
+export DEB_LDFLAGS_MAINT_APPEND = -Wl,-Bsymbolic-functions -Wl,--as-needed
 
 %:
        dh $@