patch 8.1.0662: needlessly searching for tilde in string

Problem:    Needlessly searching for tilde in string.
Solution:   Only check the first character. (James McCoy, closes #3734)
diff --git a/src/version.c b/src/version.c
index c49e869..c2869ce 100644
--- a/src/version.c
+++ b/src/version.c
@@ -800,6 +800,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    662,
+/**/
     661,
 /**/
     660,