Move the default transaction lock out of BDB environment namespace

- We dont want the transaction lock to get mixed with the BDB environment,
  nor do we want it wiped out with it as the ts lock protects things
  *around* the environment. Unlike the environment, any fcntl locks on
  the file get released when process dies, so if there is a lock,
  there's a process alive holding it and you'd better not remove it.
- Use the same lock path in macro configuration and built-in fallback
- Make it a hidden file to avoid people confusing lock file existence
  with it actually being locked

lib/rpmlock.c

@@ -14,7 +14,7 @@
 
 /* Internal interface */
 
-#define RPMLOCK_PATH LOCALSTATEDIR "/lock/rpm/transaction"
+#define RPMLOCK_PATH LOCALSTATEDIR "/rpm/.rpm.lock"
 static const char * const rpmlock_path_default = "%{?_rpmlock_path}";
 static const char * rpmlock_path = NULL;
 

macros.in

@@ -759,16 +759,8 @@ print (t)\
 %_query_all_fmt		%%{nvra}
 
 #
-# Default path to the file used for transaction fcmtl lock.
-#
-# The previous, FHS clompliant, name was /var/lock/run/transaction,
-# but the transaction lock needs to be per-database, not global, for
-# some rpmdb operations.
-#
-# XXX Note: the file name is chosen as __db.000 to expedite
-# support issues, many users are doing "rm -f /var/lib/rpm/__db*"
-# these days.
-%_rpmlock_path	%{_dbpath}/__db.000
+# Default path to the file used for transaction fcntl lock.
+%_rpmlock_path	%{_dbpath}/.rpm.lock
 
 #==============================================================================
 # ---- per-platform macros.