run-command.h: fix mis-indented struct member

An accidental conversion of a tab to 4 spaces snuck into 4c4066d95d
(run-command: move doc to run-command.h, 2019-11-17), messing up the
alignment when you have the project-recommended 8-width tabstops. Let's
revert that line.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/run-command.h b/run-command.h
index 592d9dc..0f3cc73 100644
--- a/run-command.h
+++ b/run-command.h
@@ -116,7 +116,7 @@
 	unsigned no_stdin:1;
 	unsigned no_stdout:1;
 	unsigned no_stderr:1;
-    unsigned git_cmd:1; /* if this is to be git sub-command */
+	unsigned git_cmd:1; /* if this is to be git sub-command */
 
 	/**
 	 * If the program cannot be found, the functions return -1 and set