patch 8.2.0573: using :version twice leaks memory

Problem:    using :version twice leaks memory
Solution:   Only initialize variables once. (Dominique Pelle, closes #5917)
diff --git a/src/globals.h b/src/globals.h
index 199a0c5..b474aa8 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1258,7 +1258,7 @@
 #if defined(HAVE_DATE_TIME) && defined(VMS) && defined(VAXC)
 extern char longVersion[];
 #else
-EXTERN char *longVersion;
+EXTERN char *longVersion INIT(= NULL);
 #endif
 
 /*