8205626: Start of release updates for JDK 13

8205393: Add SourceVersion.RELEASE_13
8205394: Add source 13 and target 13 to javac
8205645: Bump maximum recognized class file version to 57 for JDK 13
8214825: Update preview language features for start of JDK 13

Reviewed-by: erikj, alanb, mchung, mcimadamore, dholmes, smarks, jjg

src/hotspot/share/classfile/classFileParser.cpp

@@ -119,6 +119,8 @@
 
 #define JAVA_12_VERSION                   56
 
+#define JAVA_13_VERSION                   57
+
 void ClassFileParser::set_class_bad_constant_seen(short bad_constant) {
   assert((bad_constant == 19 || bad_constant == 20) && _major_version >= JAVA_9_VERSION,
          "Unexpected bad constant pool entry");