Fix memory leak due to enum type/val circular references

Introduced in 2982765128

CHANGES

@@ -1,4 +1,8 @@
 
+2.6-111 | 2019-01-29 18:17:35 -0600
+
+  * Fix memory leak due to enum type/val circular references (Jon Siwek, Corelight)
+
 2.6-110 | 2019-01-29 14:49:10 -0800
 
   * Add fuid to SSL:Invalid_Server_Cert notice (Stephen Hosom)

VERSION

@@ -1 +1 @@
-2.6-110
+2.6-111

src/Type.cc

@@ -1714,7 +1714,12 @@ bool EnumType::DoUnserialize(UnserialInfo* info)
 
 		names[name] = val;
 		delete [] name; // names[name] converts to std::string
-		vals[val] = new EnumVal(this, val);
+		// note: the 'vals' map gets populated lazily, which works fine and
+		// also happens to avoid a leak due to circular reference between the
+		// types and vals (there's a special case for unserializing a known
+		// type that will unserialze and then immediately want to unref the
+		// type if we already have it, except that won't delete it as intended
+		// if we've already created circular references to it here).
 		}
 
 	return true;

testing/btest/Baseline/core.leaks.broker.remote_event/send.send.out

@@ -1,4 +1,4 @@
-Broker peer added, [address=127.0.0.1, bound_port=9999/tcp]
+Broker peer added, 127.0.0.1
 got event msg, pong, 0
 got auto event msg, ping, 0
 got event msg, pong, 1

testing/btest/Baseline/core.leaks.broker.remote_log/send.send.out

@@ -1 +1 @@
-Broker peer added, [address=127.0.0.1, bound_port=9999/tcp]
+Broker peer added, 127.0.0.1

testing/external/commit-hash.zeek-testing

@@ -1 +1 @@
-42fd25c235d0c10319c3597d23f113dbbd89567f
+2f7a827cc339fc14b0c978c986fa776dd9e7903c

testing/external/commit-hash.zeek-testing-private

@@ -1 +1 @@
-e71c2dc19eabc68f590381f52a53a207f3b92f78
+60170dfea85dedd4dc9bece020d0614f04d7f30e