Have installclean remove android-info.txt again

I removed *.txt from the installclean list yesterday, but it turns out
that android-info.txt being removed was the only thing triggering
system.prop to be rebuilt on the incremental build servers. So continue
android-info.txt so that the version information in system.prop is
correct.

I'll follow this up with a more complicated change to make the
system.prop generation depend on the build number/versions more
directly, but that's a more complicated change since we need to change
how the build number file is written.

Bug: 62252890
Test: m ...intermediates/system.prop; m installclean; m ...intermediates/system.prop
Change-Id: I25dd8ddd99f7b2c927a8cbfb7f1aca1dd3e82a82

ui/build/cleanbuild.go

@@ -96,6 +96,7 @@ func installClean(ctx Context, config Config, what int) {
 		hostOut("vts"),
 		productOut("*.img"),
 		productOut("*.zip"),
+		productOut("android-info.txt"),
 		productOut("kernel"),
 		productOut("data"),
 		productOut("skin"),