patch 9.0.1519: global 'filetype' is set when detected from file content

Problem:    Global 'filetype' is set when it is detected from the file content.
Solution:   Set the local 'filetype' option value.
diff --git a/src/version.c b/src/version.c
index cf35324..2aa0ef7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1519,
+/**/
     1518,
 /**/
     1517,