[PATCH hglib] make: dist should also be a phony rule

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <raf at durin42.com>
# Date 1524677538 14400
#      Wed Apr 25 13:32:18 2018 -0400
# Node ID 9fef848282b9b8574f4897ca93390641647f4ad6
# Parent  5828b4483012dff82efacc0a6639de02b0c0b9dd
make: dist should also be a phony rule

Otherwise you have to blow away the dist/ dir before you can make a
new tarball.

diff --git a/Makefile b/Makefile
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@ help:
 
 all: help
 
-.PHONY: tests
+.PHONY: tests dist
 
 MANIFEST.in:
 	hg manifest | sed -e 's/^/include /' > MANIFEST.in