sxsyn, adjust lexing to make dot equal ligature working

src/u_sxsyn.pas

@@ -811,7 +811,16 @@ begin
     '>': lexOpAndOpOpAndOpEqualAndOpOpEqual('>');
     // `=`, `==`, `=>`
     '=': lexAssEquOrLambda();
-    '.', '(', ')', ',', ':' , '[', ']', ';' :
+    '.':
+    begin
+      nextPChar := safeLookupChar();
+      fTokKind  := TTokenKind.tkSymbl;
+      if (nextPChar <> nil) and (nextPChar^ = '=') then
+          fTokStop  += 2
+      else
+          fTokStop  += 1;
+    end;
+    '(', ')', ',', ':' , '[', ']', ';' :
     begin
       fTokKind  := TTokenKind.tkSymbl;
       fTokStop  += 1;