Fix entry point for CopyMemory

Author: GeorgRottensteiner

C64Studio/MainForm.cs

@@ -503,7 +503,6 @@ public MainForm( string[] args )
       debugToolStripMenuItem.Visible = false;
 #endif
 
-
       statusProgress.Visible = false;
 
       StudioCore.MainForm = this;

Common/Common/FastImage.cs

@@ -174,9 +174,11 @@ public override bool Equals( object Object )
     static extern bool InvalidateRect( IntPtr hWnd, IntPtr lpRect, bool bErase );
     [DllImport( "user32.dll" )]
     static extern bool ValidateRect( IntPtr hWnd, ref GR.Image.FastImage.RECT lpRect );
-
-    //[DllImport( "Kernel32.dll", EntryPoint = "CopyMemory" )]
-    [DllImport( "Kernel32.dll", EntryPoint = "RtlCopyMemory" )]   // not working in Ubuntu?
+#if NET5_0_OR_GREATER
+    [DllImport( "Kernel32.dll", EntryPoint = "RtlCopyMemory" )]
+#else
+    [DllImport( "Kernel32.dll", EntryPoint = "CopyMemory" )]
+#endif
     static extern void CopyMemory( IntPtr dest, IntPtr src, uint length );
 
     [DllImport( "user32.dll" )]