unicode: move scripts from FoldCategories to FoldScripts

Copy-and-paste bug was putting scripts in the categories map.

Fixes #18186.

Change-Id: Ife9d9bdd346fe24e578dbb2a0aac7ef6e889ae68
Reviewed-on: https://go-review.googlesource.com/45830
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/unicode/maketables.go b/src/unicode/maketables.go
index e52d9c2..42864b4 100644
--- a/src/unicode/maketables.go
+++ b/src/unicode/maketables.go
@@ -1201,7 +1201,7 @@
 	scr := make(map[string]map[rune]bool)
 	for name := range scripts {
 		if x := foldExceptions(inScript(name)); len(x) > 0 {
-			cat[name] = x
+			scr[name] = x
 		}
 	}