devtools: Accomodate block-style copyright blocks
devtools: Accomodate block-style copyright blocks

Without this, `copyright_header.py report . verbose` reports:
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1 with unexpected copyright holder names
	./build_msvc/libsecp256k1_config.h
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peercoin/peercoin,DigitalPandacoin/pandacoin,DigitalPandacoin/pandacoin,peercoin/peercoin,DigitalPandacoin/pandacoin,DigitalPandacoin/pandacoin,peercoin/peercoin,DigitalPandacoin/pandacoin,peercoin/peercoin,DigitalPandacoin/pandacoin,peercoin/peercoin,peercoin/peercoin