patch 8.0.0250: virtcol() does not work well for multi-byte characters

Problem:    When virtcol() gets a column that is not the first byte of a
            multi-byte character the result is unpredictable. (Christian
            Ludwig)
Solution:   Correct the column to the first byte of a multi-byte character.
            Change the utf-8 test to new style.
diff --git a/src/Makefile b/src/Makefile
index a588219..f993c85 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2058,7 +2058,6 @@
 	test_listlbr \
 	test_listlbr_utf8 \
 	test_search_mbyte \
-	test_utf8 \
 	test_wordcount \
 	test3 test4 test5 test6 test7 test8 test9 \
 	test11 test12 test14 test15 test17 test18 test19 \
@@ -2183,6 +2182,7 @@
 	test_undo \
 	test_unlet \
 	test_usercommands \
+	test_utf8 \
 	test_viminfo \
 	test_viml \
 	test_visual \