[GH #843] warnings: Improve clang support
[GH #843] warnings: Improve clang support

clang requires warnings overrides for -Wno-parentheses-equality
and adds -Wno-unused-result to src/ops/core_ops.c.
(used in 29582199aef9ea9462 [GH #828] Optimize print_n/i and say_n/i)

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