patch 8.2.3001: Vim9: memory leak when compilation fails

Problem:    Vim9: memory leak when compilation fails.
Solution:   Free the list of variable names.

Author: brammool

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3001,
 /**/
     3000,
 /**/

src/vim9compile.c

@@ -9724,8 +9724,10 @@ compile_def_function(
 	dfunc_T	*dfunc = ((dfunc_T *)def_functions.ga_data)
 							 + ufunc->uf_dfunc_idx;
 
+	// Compiling aborted, free the generated instructions.
 	clear_instr_ga(instr);
 	VIM_CLEAR(dfunc->df_name);
+	ga_clear_strings(&dfunc->df_var_names);
 
 	// If using the last entry in the table and it was added above, we
 	// might as well remove it.