run-command: prettify the `RUN_COMMAND_*` flags

The values were listed unaligned, and with powers of two spelled out in
decimal. The list is easier to parse for human readers if the numbers
are aligned and spelled out as powers of two (using the bit-shift
operator `<<`).

While at it, remove a code comment that was unclear at best, and
confusing at worst.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

run-command.h

@@ -233,13 +233,13 @@ int run_hook_ve(const char *const *env, const char *name, va_list args);
  */
 int run_auto_maintenance(int quiet);
 
-#define RUN_COMMAND_NO_STDIN 1
-#define RUN_GIT_CMD	     2	/*If this is to be git sub-command */
-#define RUN_COMMAND_STDOUT_TO_STDERR 4
-#define RUN_SILENT_EXEC_FAILURE 8
-#define RUN_USING_SHELL 16
-#define RUN_CLEAN_ON_EXIT 32
-#define RUN_WAIT_AFTER_CLEAN 64
+#define RUN_COMMAND_NO_STDIN		(1<<0)
+#define RUN_GIT_CMD			(1<<1)
+#define RUN_COMMAND_STDOUT_TO_STDERR	(1<<2)
+#define RUN_SILENT_EXEC_FAILURE		(1<<3)
+#define RUN_USING_SHELL			(1<<4)
+#define RUN_CLEAN_ON_EXIT		(1<<5)
+#define RUN_WAIT_AFTER_CLEAN		(1<<6)
 
 /**
  * Convenience functions that encapsulate a sequence of