tests: factor out VERBOSE-only --version-printing code

* tests/init.cfg (print_ver_): New function.

tests/init.cfg

@@ -399,4 +399,16 @@ retry_delay_()
   test "$time_fail" = 0
 }
 
+# Call this with a list of programs under test immediately after
+# sourcing init.sh.
+print_ver_()
+{
+  if test "$VERBOSE" = yes; then
+    local i
+    for i in $*; do
+      env $i --version
+    done
+  fi
+}
+
 sanitize_path_