Fix writedonechan size in Venti Bloom.

It fixes a crash on Venti Bloom, when
running the Plan 9 64-bit kernel.

The writedonechan Channel was incorrectly
allocated with a size of void* instead
unsigned long. This is a problem on Plan 9
because the type long is always 32-bit on
both 32-bit and 64-bit systems.

This change has been reviewed and merged
in plan9port.

Reference: /n/sources/patch/applied/venti-bloom-writedonechan
Date: Wed May  2 07:57:14 CES 2012
Signed-off-by: djc@9grid.fr

--- /sys/src/cmd/venti/srv/bloom.c	Wed May  2 07:57:02 2012
+++ /sys/src/cmd/venti/srv/bloom.c	Wed May  2 07:56:59 2012
@@ -251,6 +251,6 @@
 startbloomproc(Bloom *b)
 {
 	b->writechan = chancreate(sizeof(void*), 0);
-	b->writedonechan = chancreate(sizeof(void*), 0);
+	b->writedonechan = chancreate(sizeof(ulong), 0);
 	vtproc(bloomwriteproc, b);	
 }