patch 8.2.4990: memory leak when :defcompile fails

Problem:    Memory leak when :defcompile fails.
Solution:   Free fname when returning early.
diff --git a/src/version.c b/src/version.c
index c6e6a39..6cb825c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4990,
+/**/
     4989,
 /**/
     4988,