Add "PT" log domain.

See: https://bugs.torproject.org/28179

doc/tor.1.txt

@@ -669,8 +669,8 @@ GENERAL OPTIONS
  +
     The currently recognized domains are: general, crypto, net, config, fs,
     protocol, mm, http, app, control, circ, rend, bug, dir, dirserv, or, edge,
-    acct, hist, handshake, heartbeat, channel, sched, guard, consdiff, dos, and
-    process.
+    acct, hist, handshake, heartbeat, channel, sched, guard, consdiff, dos,
+    process, and pt.
     Domain names are case-insensitive. +
  +
     For example, "`Log [handshake]debug [~net,~mm]info notice stdout`" sends

src/lib/log/log.c

@@ -1268,7 +1268,7 @@ static const char *domain_list[] = {
   "GENERAL", "CRYPTO", "NET", "CONFIG", "FS", "PROTOCOL", "MM",
   "HTTP", "APP", "CONTROL", "CIRC", "REND", "BUG", "DIR", "DIRSERV",
   "OR", "EDGE", "ACCT", "HIST", "HANDSHAKE", "HEARTBEAT", "CHANNEL",
-  "SCHED", "GUARD", "CONSDIFF", "DOS", "PROCESS", NULL
+  "SCHED", "GUARD", "CONSDIFF", "DOS", "PROCESS", "PT", NULL
 };
 
 /** Return a bitmask for the log domain for which <b>domain</b> is the name,

src/lib/log/log.h

@@ -109,8 +109,10 @@
 #define LD_DOS       (1u<<25)
 /** Processes */
 #define LD_PROCESS   (1u<<26)
+/** Pluggable Transports. */
+#define LD_PT        (1u<<27)
 /** Number of logging domains in the code. */
-#define N_LOGGING_DOMAINS 27
+#define N_LOGGING_DOMAINS 28
 
 /** This log message is not safe to send to a callback-based logger
  * immediately.  Used as a flag, not a log domain. */