Added the the define constants NET40PLUS and NET45PLUS to the .NET Core runtime project.

runtime/CSharp/runtime/CSharp/Antlr4.Runtime/Dfa/ArrayEdgeMap.cs

@@ -34,7 +34,7 @@ using Antlr4.Runtime.Dfa;
 using Antlr4.Runtime.Sharpen;
 using Interlocked = System.Threading.Interlocked;
 
-#if NET45PLUS || DOTNETCORE
+#if NET45PLUS
 using Volatile = System.Threading.Volatile;
 #elif !PORTABLE && !COMPACT
 using Thread = System.Threading.Thread;
@@ -60,7 +60,7 @@ namespace Antlr4.Runtime.Dfa
         {
             get
             {
-#if NET45PLUS || DOTNETCORE
+#if NET45PLUS
                 return Volatile.Read(ref size);
 #elif !PORTABLE && !COMPACT
                 return Thread.VolatileRead(ref size);

runtime/CSharp/runtime/CSharp/Antlr4.Runtime/Sharpen/Compat/ConcurrentDictionary.cs

@@ -22,7 +22,7 @@
 //
 //
 
-#if (!NET40PLUS && !DOTNETCORE) || (PORTABLE && !WINRT)
+#if !NET40PLUS || (PORTABLE && !WINRT)
 
 using System;
 using System.Threading;

runtime/CSharp/runtime/CSharp/Antlr4.Runtime/Sharpen/Compat/Tuple.cs

@@ -26,7 +26,7 @@
 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-#if !NET40PLUS && !DOTNETCORE
+#if !NET40PLUS
 
 using System;
 

runtime/CSharp/runtime/CSharp/Antlr4.Runtime/Sharpen/Compat/Tuples.cs

@@ -27,7 +27,7 @@
 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-#if !NET40PLUS && !DOTNETCORE
+#if !NET40PLUS
 
 using System;
 using System.Collections;

runtime/CSharp/runtime/CSharp/project.json

@@ -1,6 +1,6 @@
 {
   "buildOptions": {
-    "define": [ "DEBUG", "TRACE", "DOTNETCORE" ],
+    "define": [ "DEBUG", "TRACE", "DOTNETCORE", "NET40PLUS", "NET45PLUS" ],
     "keyFile": "../Antlr4.snk",
     "xmlDoc": true
   },