possible workaround for OS X Lion compile hang

[Colin Percival <cperciva@tarsnap.com>]

Hi all,

I've attached a patch which might work around the llvm-gcc bug which is making
the Tarsnap build hang on OS X Lion.  Can someone please test this and let me
know?  I've managed to reproduce "llvm-gcc is really slow on this one file" on
my local (FreeBSD) system but I'm only seeing it take ~10 seconds for that file
instead of hanging completely so I'm not sure if I've got exactly the same buggy
llvm-gcc code path being triggered.

-- 
Colin Percival
Security Officer, FreeBSD | freebsd.org | The power to serve
Founder / author, Tarsnap | tarsnap.com | Online backups for the truly paranoid

--- ./tar/multitape/chunkify.c	2011-12-28 11:15:36.000000000 -0800
+++ ./tar/multitape/chunkify.c	2012-01-14 15:13:27.000000000 -0800
@@ -67,7 +67,7 @@
 static uint32_t
 nextprime(uint32_t n)
 {
-	uint32_t p;
+	volatile uint32_t p;
 
 	for (p = n; p != 0; p++)
 		if (isprime(p))