[gold patch] Add Swap_aligned32 template for writing gdb index

[David Miller]

From: Cary Coutant <ccoutant@google.com>
Date: Mon, 23 Apr 2012 15:40:47 -0700

> Tested on x86_64. (Should also be tested on sparc -- David, can you
> try this out?)

Works fine on both 32-bit and 64-bit sparc.