make: use shell-command assignment instead of $(eval ...) This is portable between BSD and GNU make. As of this change, our Makefile appears to work in both BSD and GNU make, with the caveat that the test-% and testpy-% wildcard rules don't work on BSD make. That said, this still seems worthwhile because it lets the buildbots work more consistently across platforms.

--- a/Makefile	Thu Apr 21 10:10:48 2016 -0400
+++ b/Makefile	Thu Apr 21 10:11:20 2016 -0400
@@ -6,7 +6,7 @@
 
 export PREFIX=/usr/local
 PYTHON=python
-$(eval HGROOT := $(shell pwd))
+HGROOT != pwd
 HGPYTHONS ?= $(HGROOT)/build/pythons
 PURE=
 PYFILES:=$(shell find mercurial hgext doc -name '*.py')