git-mailrc: add patman and buildman alias

It's easier to Cc Simon on patches related to Patman or Buildman.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Simon Glass <sjg@chromium.org>

doc/git-mailrc

@@ -119,3 +119,5 @@ alias net            uboot, jhersh
 alias spi	     uboot, jagan
 alias usb            uboot, marex
 alias video          uboot, ag
+alias patman         uboot, sjg
+alias buildman       uboot, sjg