SMB fixes and cleanup.

SMB error handling improved. The analyzer isn't destroyed when a problem
is encoutered anymore.  The flowbuffer in the parser is now flushed and
the analyzer is set to resync against an SMB command.  This was needed
because there is some state about open files that is kept within the
parser itself which was being destroyed and that was causing analysis
after content gaps or parse errors to be faulty.  The new mechanism
doesn't detroy the parser so parsing after gaps is improved.

DCE_RPC handling in SMB is improved in the edge case where a drive
mapping isn't seen. There is a new const named SMB::pipe_filenames
which is used as a heuristic for identifying "files" opened on named
pipe shares.  If the share mapping type isn't known and a filename
in this set is found, the share type will change to "PIPE" by
generating an event named "smb_pipe_connect_heuristic".  Reads and
writes to that file will be sent to the DCE_RPC analyzer instead of
to the files framework.

The concept of "unknown" share types has been removed due to the new
heuristic detection of share types.

Some general clean up of how the SMB cmd log is written and when.

scripts/base/protocols/smb/consts.bro

@@ -10,20 +10,18 @@ export {
 		[0x00000000] = [$id="SUCCESS", $desc="The operation completed successfully."],
 	} &redef &default=function(i: count):StatusCode { local unknown=fmt("unknown-%d", i); return [$id=unknown, $desc=unknown]; };
 
-	## These are files names that are used for special 
-	## cases by the file system and would not be 
-	## considered "normal" files.
-	const pipe_names: set[string] = {
-		"\\netdfs",
-		"\\spoolss",
-		"\\NETLOGON",
-		"\\winreg",
-		"\\lsarpc",
-		"\\samr",
-		"\\srvsvc",
+	## Heuristic detection of named pipes when the pipe
+	## mapping isn't seen. This variable is defined in
+	## init-bare.bro.
+	redef SMB::pipe_filenames = {
+		"spoolss",
+		"winreg",
+		"samr",
 		"srvsvc",
+		"netdfs",
+		"lsarpc",
+		"wkssvc",
 		"MsFteWds",
-		"\\wkssvc",
 	};
 
 	## The UUIDs used by the various RPC endpoints