Make 'run' use run_command_list() instead of run_command()

In the case where an environment variable spans multiple lines, we should
use run_command_list() so that all lines are executed. This shold be
backwards compatible with existing behaviour for existing scripts.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/main.c b/common/main.c
index e54f63b..9bee7bd 100644
--- a/common/main.c
+++ b/common/main.c
@@ -1550,7 +1550,7 @@
 			return 1;
 		}
 
-		if (run_command(arg, flag) != 0)
+		if (run_command_list(arg, -1, flag) != 0)
 			return 1;
 	}
 	return 0;