patch 9.0.2120: un-used assignment in do_source_buffer_init

Problem:  un-used assignment in do_source_buffer_init
Solution: Remove it

Coverity warns about assigning NULL to line in scriptfile.c:1408,
because right after that assignment, in the next iteration of the loop,
line will be overwritten by the next value from vim_strsave().

And in case this was the last iteration, the line variable is no longer
used until the function returns. So we can safely remove that assignment.

closes: #13547

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 9379c26..edf6b57 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2120,
+/**/
     2119,
 /**/
     2118,