Fix build where memcpy is a macro

[alyssais]

I got the following compiler error with Clang 16 building for x86_64-apple-darwin:

/tmp/nix-build-canokey-qemu-0-unstable-2023-06-06.drv-0/source/canokey-core/applets/oath/oath.c:44:50: error: too many arguments provided to function-like macro invocation
  memcpy(RDATA, (uint8_t[]){OATH_TAG_VERSION, 3, 0x05, 0x05, 0x05, OATH_TAG_NAME, HANDLE_LEN}, 7);
                                                 ^
/nix/store/vw8y07yai2pjv02s1piw3r5cyhmjbddf-Libsystem-1238.60.2/include/secure/_string.h:64:9: note: macro 'memcpy' defined here
#define memcpy(dest, src, len)                                  \
        ^
/tmp/nix-build-canokey-qemu-0-unstable-2023-06-06.drv-0/source/canokey-core/applets/oath/oath.c:44:3: note: parentheses are required around macro argument containing braced initializer list
  memcpy(RDATA, (uint8_t[]){OATH_TAG_VERSION, 3, 0x05, 0x05, 0x05, OATH_TAG_NAME, HANDLE_LEN}, 7);
  ^
                (                                                                            )
1 error generated.