[dconf] workaround OpenBSD mmap() bug

[Ryan Lortie <ryanl src gnome org>]

commit bcd9ea89be7232d45d40a647660472c1f7ada61e
Author: Antoine Jacoutot <ajacoutot gnome org>
Date:   Thu Nov 1 12:17:04 2012 +0100

    workaround OpenBSD mmap() bug
    
    On OpenBSD, mapping descriptors PROT_WRITE without also specifying
    PROT_READ triggers a segfault.

 shm/dconf-shm.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/shm/dconf-shm.c b/shm/dconf-shm.c
index 10bfec9..e47e377 100644
--- a/shm/dconf-shm.c
+++ b/shm/dconf-shm.c
@@ -134,7 +134,7 @@ dconf_shm_flag (const gchar *name)
            *
            * Using mmap() works everywhere.
            */
-          shm = mmap (NULL, 1, PROT_WRITE, MAP_SHARED, fd, 0);
+          shm = mmap (NULL, 1, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
           g_assert (shm != MAP_FAILED);
 
           *shm = 1;