RFR: 8234835 Use UTF-8 charset in make support Java code

[Dan Smith]

> For the other files, it seems strange to force the use of a charset 
> which is different from the charset of record for all our source files 
> (i.e. US-ASCII).

Can you clarify where this "charset of record" rule comes from? Is this written down somewhere, or more of an oral tradition?

The non-ASCII characters I'm working with are, in fact, in the original Markdown sources. If it's really important to avoid those in all sources, I could (reluctantly) use a different strategy.

If the consensus is that the build tools should standardize on US-ASCII, I guess there's a separate question about whether we're willing to rely on the implicit platform default (now uniformly US-ASCII via command-line args), or whether it's better to be explicit about it (s/UTF_8/US_ASCII/ in my changeset).