cmake HAVE_DECL_BSWAP_64 examples

Bitcoin-ABC/bitcoin-abc src/config/CMakeLists.txt :53 

check_symbol_exists(bswap_64 "byteswap.h" HAVE_DECL_BSWAP_64)

bitcoin-sv/bitcoin-sv src/config/CMakeLists.txt :64 

check_symbol_exists(bswap_64 "byteswap.h" HAVE_DECL_BSWAP_64)

ngtcp2/ngtcp2 CMakeLists.txt :336 

check_symbol_exists(bswap_64 "byteswap.h" HAVE_DECL_BSWAP_64)