http2: remove unused nghttp2 error list
Remove a list of HTTP2 errors as well as nghttp2_errname()
that converted an integer nghttp2 error code to a string
representation.
We already use nghttp2_strerror()
for this, which
is provided by nghttp2 returns a better error string anyway.
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
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