vbscript: Fix compile when statement after ElseIf or after separator.

dlls/vbscript/parser.y

@@ -314,7 +314,7 @@ ElseIfs
     | ElseIf ElseIfs                        { $1->next = $2; $$ = $1; }
 
 ElseIf
-    : tELSEIF Expression tTHEN tNL StatementsNl_opt
+    : tELSEIF Expression tTHEN StSep_opt StatementsNl_opt
                                             { $$ = new_elseif_decl(ctx, @$, $2, $5); }
 
 Else_opt

dlls/vbscript/tests/lang.vbs

@@ -337,6 +337,23 @@ ElseIf not False Then
 End If
 Call ok(x, "elseif not called?")
 
+' ElseIf with statement on same line
+x = false
+If false Then
+   Call ok(false, "inside if false")
+ElseIf not False Then x = true
+End If
+Call ok(x, "elseif not called?")
+
+' ElseIf with statement following statement separator
+x = false
+If false Then
+   Call ok(false, "inside if false")
+ElseIf not False Then
+: x = true
+End If
+Call ok(x, "elseif not called?")
+
 x = false
 if 1 then x = true
 Call ok(x, "if 1 not run?")