YANG runtime impl package consolidation & YANG compiler's YangLexer package correction.

Change-Id: I86ebebf5e15f17e32eda31db65ae55fdf11bc6f9
diff --git a/compiler/base/parser/src/main/resources/YangLexer.g4 b/compiler/base/parser/src/main/resources/YangLexer.g4
index 51a9231..45189f7 100644
--- a/compiler/base/parser/src/main/resources/YangLexer.g4
+++ b/compiler/base/parser/src/main/resources/YangLexer.g4
@@ -20,6 +20,10 @@
 
 lexer grammar YangLexer;
 
+@header {
+package org.onosproject.yang.compiler.parser.antlrgencode;
+}
+
     // Statements keywords
     ANYXML_KEYWORD      : 'anyxml';
     ARGUMENT_KEYWORD    : 'argument';