net/quiche: fix powerpc64* build
In file included from /wrkdirs/usr/ports/net/quiche/work/target/release/build/boring-sys-e26f46e56ac7f264/out/boringssl/err_data.c:17:
/wrkdirs/usr/ports/net/quiche/work/target/release/build/boring-sys-e26f46e56ac7f264/out/boringssl/src/include/openssl/base.h:124:2: error: "Unknown target CPU"
124 | #error "Unknown target CPU"
| ^
1 error generated.