Do not try to make phpstan on PHP 7.0

Makefile

@@ -384,8 +384,17 @@ vendor-bin/phan/vendor: vendor/bamarni/composer-bin-plugin vendor-bin/phan/compo
 vendor-bin/phan/composer.lock: vendor-bin/phan/composer.json
 	@echo phan composer.lock is not up to date.
 
+# The first line of "php --version" output looks like:
+# PHP 7.2.16-1+ubuntu18.04.1+deb.sury.org+1 (cli) (built: Mar  7 2019 20:23:29) ( NTS )
+# We want the 2nd "word", then the first 2 numbers separated by the dot
+PHP_MINOR_VERSION = $(shell php --version | head -n 1 | cut -d' ' -f2 | cut -d'.' -f1-2)
+
 vendor-bin/phpstan/vendor: vendor/bamarni/composer-bin-plugin vendor-bin/phpstan/composer.lock
+ifeq "$(PHP_MINOR_VERSION)" "7.0"
+	@echo "phpstan is not supported on PHP 7.0 so it is not being installed"
+else
 	composer bin phpstan install --no-progress
+endif
 
 vendor-bin/phpstan/composer.lock: vendor-bin/phpstan/composer.json
 	@echo phpstan composer.lock is not up to date.