patch 8.2.3299: Vim9: exists() does not handle much at compile time

Problem:    Vim9: exists() does not handle much at compile time.
Solution:   Handle variable names. (closes #8688)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 6db930e..af46d15 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -3552,7 +3552,14 @@
     }
     else if (*p == '*')			// internal or user defined function
     {
+	int save_version = current_sctx.sc_version;
+
+	// Vim9 script assumes a function is script-local, but here we want to
+	// find any matching function.
+	if (current_sctx.sc_version == SCRIPT_VERSION_VIM9)
+	    current_sctx.sc_version = SCRIPT_VERSION_MAX;
 	n = function_exists(p + 1, FALSE);
+	current_sctx.sc_version = save_version;
     }
     else if (*p == '?')			// internal function only
     {