patch 8.0.0614: float2nr() is not exactly right

Problem:    float2nr() is not exactly right.
Solution:   Make float2nr() more accurate.  Turn test64 into a new style test.
            (Hirohito Higashi, closes #1688)
diff --git a/src/Makefile b/src/Makefile
index 8fa004e..500b074 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2087,7 +2087,7 @@
 	test30 test31 test32 test33 test34 test36 test37 test38 test39 \
 	test40 test41 test42 test43 test44 test45 test48 test49 \
 	test50 test51 test52 test53 test54 test55 test56 test57 test58 test59 \
-	test60 test64 test65 test66 test67 test68 test69 \
+	test60 test64 test66 test67 test68 test69 \
 	test70 test72 test73 test74 test75 test77 test78 test79 \
 	test80 test82 test83 test84 test85 test86 test87 test88 \
 	test90 test91 test94 test95 test97 test98 test99 \