add emacs editing/indent rules

I'm just reusing mesa, I dislike mesa but it makes it easier
to deal with gallium

.dir-locals.el

@@ -0,0 +1,12 @@
+((prog-mode
+  (indent-tabs-mode . nil)
+  (tab-width . 8)
+  (c-basic-offset . 3)
+  (c-file-style . "stroustrup")
+  (fill-column . 78)
+  (eval . (progn
+	    (c-set-offset 'innamespace '0)
+	    (c-set-offset 'inline-open '0)))
+  )
+ (makefile-mode (indent-tabs-mode . t))
+ )