gdscript tokenizer will dislike use of case, closes #4991

(cherry picked from commit ceeb5453a8)

modules/gdscript/gd_tokenizer.cpp

@@ -79,8 +79,8 @@ const char* GDTokenizer::token_names[TK_MAX]={
 "for",
 "do",
 "while",
-"switch",
-"case",
+"switch (reserved)",
+"case (reserved)",
 "break",
 "continue",
 "pass",
@@ -874,6 +874,7 @@ void GDTokenizerText::_advance() {
 								{TK_CF_WHILE,"while"},
 								{TK_CF_DO,"do"},
 								{TK_CF_SWITCH,"switch"},
+								{TK_CF_CASE,"case"},
 								{TK_CF_BREAK,"break"},
 								{TK_CF_CONTINUE,"continue"},
 								{TK_CF_RETURN,"return"},