cmd/gomobile: use the correct case for the generated Universe.objc.h file

Fixes golang/go#28335

Change-Id: Ia6ef4a5e9c426d810770459632ab276eea9cab8f
GitHub-Last-Rev: 47d9c16539e6fd0e154d45e39248240650877356
GitHub-Pull-Request: golang/mobile#24
Reviewed-on: https://go-review.googlesource.com/c/144117
Reviewed-by: Elias Naur <elias.naur@gmail.com>
diff --git a/cmd/gomobile/bind_iosapp.go b/cmd/gomobile/bind_iosapp.go
index 7b7fe69..2c129b0 100644
--- a/cmd/gomobile/bind_iosapp.go
+++ b/cmd/gomobile/bind_iosapp.go
@@ -53,7 +53,7 @@
 	for i, pkg := range pkgs {
 		fileBases[i] = bindPrefix + strings.Title(pkg.Name)
 	}
-	fileBases[len(fileBases)-1] = "universe"
+	fileBases[len(fileBases)-1] = "Universe"
 
 	cmd = exec.Command("xcrun", "lipo", "-create")