converted all our existing shared memory code to use a tdb database

instead of either sysv or mmap shared memory or lock files.

this means we can now completely remove
	locking_shm.c
	locking_slow.c
	shmem.c
	shmem_sysv.c
and lots of other things also got simpler

locking.c got a bit larger, but is much better compartmentalised now

source/lib/util.c

@@ -3213,3 +3213,24 @@ char *myhostname(void)
 	}
 	return ret;
 }
+
+
+/*****************************************************************
+a useful function for returning a path in the Samba lock directory
+ *****************************************************************/  
+char *lock_path(char *name)
+{
+	static pstring fname;
+
+	pstrcpy(fname,lp_lockdir());
+	trim_string(fname,"","/");
+	
+	if (!directory_exist(fname,NULL)) {
+		mkdir(fname,0755);
+	}
+	
+	pstrcat(fname,"/");
+	pstrcat(fname,name);
+
+	return fname;
+}