patch 8.0.1295: cannot automatically get a server name in a terminal

Problem:    Cannot automatically get a server name in a terminal.
Solution:   Add the --enable-autoservername flag to configure. (Cimbali,
            closes #2317)
diff --git a/src/config.h.in b/src/config.h.in
index e692d40..ec9fc59 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -384,6 +384,9 @@
 /* Define if you want to include multibyte support. */
 #undef FEAT_MBYTE
 
+/* Define if you want to always define a server name at vim startup. */
+#undef FEAT_AUTOSERVERNAME
+
 /* Define if you want to include fontset support. */
 #undef FEAT_XFONTSET