patch 8.1.1090: MS-Windows: modify_fname() has problems with some 'encoding'

Problem:    MS-Windows: modify_fname() has problems with some 'encoding'.
Solution:   Use GetLongPathNameW() instead of GetLongPathName(). (Ken Takata,
            closes #4007)
diff --git a/src/version.c b/src/version.c
index 21152b0..0f62b83 100644
--- a/src/version.c
+++ b/src/version.c
@@ -776,6 +776,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1090,
+/**/
     1089,
 /**/
     1088,