RFR (tedious) 8216022: Use #pragma once

[Andrew Haley]

On 1/4/19 11:07 AM, Florian Weimer wrote:
> The guards occasionally cause bugs because they are not globally unique
> or not spelled correctly in both places in the header file.

Yeah, I know. That's the usual non-performance-related pro-#pragma
once argument. After GCC and a bunch of other compilers implemented
optimized include guards I thought that #pragma once would go away,
but evidently not.  :-)

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671