: upgrade to CLDR 28 and necessary adjustments

cldr:
- needed to excluded "validity" directory as it contains xml data
  not specific to locales.

language and internal:
- CompactIndex now supports *all* locales for which there are data
  files and not just the ones which have data. This is necessary to
  not drop en-US. Seems better anyway. This increases table size, but
  added comment about a trick that could be used to reduce it again in
  the future.
- Skipping more match data entries. My suspicion is that this is
  supported anyway, but needs to be verified (TODO added).

language/display:
- manually removed support for "private use" script names are their
  coverage is spotty and questionable.
- manually override coverage test for az_Arab: not supported by
  English, but seems to have good data for languages for which this
  may be relevant.

currency:
- minor changes in test code and generation code to adapt to
  change data.
- manually added MVP as currency as it doesn't appear to be added
  otherwise.

Note that search and collate are still stuck on old revisions.

Change-Id: I2b2b2cba66caaff7c027fcb421f99595430e31dd
Reviewed-on: https://go-review.googlesource.com/17802
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
diff --git a/language/display/maketables.go b/language/display/maketables.go
index 48a461e..3fcd9c8 100644
--- a/language/display/maketables.go
+++ b/language/display/maketables.go
@@ -215,7 +215,16 @@
 	b.setData("script", func(g *group, loc language.Tag, ldn *cldr.LocaleDisplayNames) {
 		if ldn.Scripts != nil {
 			for _, v := range ldn.Scripts.Script {
-				g.set(loc, language.MustParseScript(v.Type).String(), v.Data())
+				code := language.MustParseScript(v.Type)
+				if code.IsPrivateUse() { // Qaaa..Qabx
+					// TODO: data currently appears to be very meager.
+					// Reconsider if we have data for English.
+					if loc == language.English {
+						log.Fatal("Consider including data for private use scripts.")
+					}
+					continue
+				}
+				g.set(loc, code.String(), v.Data())
 			}
 		}
 	})