Add region-size patch for posterity

build/db.4.2.52.patch

+As posted to http://www.openldap.org/lists/openldap-devel/200610/msg00027.html
+
+This is Sleepycat bug #14908. The provided patch is for 4.2.52. The
+same bug is present in all versions up to 4.5.20 where it is fixed.
+
+-------- Original Message --------
+Subject: region size bug Re: [BDB-Alpha] Berkeley DB 4.5.8 ALPHA
+Date: Mon, 10 Jul 2006 13:37:33 -0700
+From: Howard Chu <hyc@symas.com>
+To: support@sleepycat.com
+CC: support@symas.com
+References: <45A742B5-7DD5-4512-A204-A10FE8FC5DFC@oracle.com>
+
+
+I just ran into this in 4.2.52 but the same calculation occurs in 4.4
+and 4.5.8 alpha:
+
+This computation gives the wrong results when the number of cache
+regions is greater than the number of gigabytes (which we encounter on
+Linux using shared memory regions, which are constrained to much smaller
+than a gigabyte each).
+
+
+in mp/mp_region.c:
+
+
+   roff_t reg_size;
+
+
+   /* Figure out how big each cache region is. */
+   reg_size = (roff_t)(dbenv->mp_gbytes / dbenv->mp_ncache) * GIGABYTE;
+   reg_size += ((roff_t)(dbenv->mp_gbytes %
+       dbenv->mp_ncache) * GIGABYTE) / dbenv->mp_ncache;
+   reg_size += dbenv->mp_bytes / dbenv->mp_ncache;
+   *reg_sizep = reg_size;
+
+
+The first reg_size calculation always goes to zero when mp_ncache >
+mp_gbytes.
+This should have been, instead:
+   reg_size = GIGABYTE / dbenv->mp_ncache * dbenv->mp_gbytes;
+
+--- mp/mp_region.c.O	2003-06-30 10:20:19.000000000 -0700
++++ mp/mp_region.c	2006-10-27 23:25:05.000000000 -0700
+@@ -43,9 +43,7 @@
+ 	int htab_buckets, ret;
+ 
+ 	/* Figure out how big each cache region is. */
+-	reg_size = (dbenv->mp_gbytes / dbenv->mp_ncache) * GIGABYTE;
+-	reg_size += ((dbenv->mp_gbytes %
+-	    dbenv->mp_ncache) * GIGABYTE) / dbenv->mp_ncache;
++	reg_size = GIGABYTE / dbenv->mp_ncache * dbenv->mp_gbytes;
+ 	reg_size += dbenv->mp_bytes / dbenv->mp_ncache;
+ 
+ 	/*