It's "gmake dist" now.

src/tools/release_prep

-#! /bin/sh
-#
-# release_prep: prepare the Postgres source tree for distribution
-#
-# This script should be run after checking out a fileset from the Postgres
-# CVS repository, and just before creating a tarfile from the checked-out
-# fileset.  It does cleanup tasks to ensure that we have a good tarball.
-#
-# Run the script from the toplevel Postgres directory, ie, do
-#	cd pgsql
-#	src/tools/release_prep
-#
-# The script's tasks are:
-# 1. Run configure to prepare usable Makefiles on the local system.
-# 2. Generate distribution copies of some derived files such as gram.c.
-#    (We do this so that recipients of the distribution don't have to have
-#    tools that can create these files.)
-# 3. "make distclean" to get rid of the configure outputs, as well as any
-#    other cruft that might be laying about.
-
-# Select make to use --- default gmake, can be overridden by env var
-: ${MAKE=gmake}
-
-./configure && \
-$MAKE distprep && \
-$MAKE distclean