Mark print-% target as phony.

.PHONY does not take patterns (such as print-%) as prerequisites.
Have print-% depend on FORCE and mark FORCE as phony.

$ # on master
$ make print-host
host=x86_64-pc-linux-gnu
$ touch print-host
$ make print-host
make: 'print-host' is up to date.
$
$ git co mark_print_as_phony
Switched to branch 'mark_print_as_phony'
$ make print-host
host=x86_64-pc-linux-gnu
$ touch FORCE
$ make print-host
host=x86_64-pc-linux-gnu

Makefile.am

@@ -3,7 +3,7 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 # Pattern rule to print variables, e.g. make print-top_srcdir
-print-%:
+print-%: FORCE
 	@echo '$*'='$($*)'
 
 ACLOCAL_AMFLAGS = -I build-aux/m4