build on alpine linux ppc64le and aarch64 fails with: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]

[ncopa]

It seems like build fails on anything that is not x86_64:

On ppc64le:

/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp: In function 'int8_t beast::http::detail::unhex(char)':
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
     };
     ^
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
...
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
make[2]: *** [CMakeFiles/rippled.dir/build.make:455: CMakeFiles/rippled.dir/src/ripple/unity/overlay.cpp.o] Error 1
make[2]: *** [CMakeFiles/rippled.dir/build.make:167: CMakeFiles/rippled.dir/src/ripple/unity/app_ledger.cpp.o] Error 1
make[2]: *** [CMakeFiles/rippled.dir/build.make:191: CMakeFiles/rippled.dir/src/ripple/unity/app_main.cpp.o] Error 1
make[2]: *** [CMakeFiles/rippled.dir/build.make:215: CMakeFiles/rippled.dir/src/ripple/unity/app_misc.cpp.o] Error 1
make[2]: *** [CMakeFiles/rippled.dir/build.make:623: CMakeFiles/rippled.dir/src/test/unity/app_test_unity.cpp.o] Error 1
make[2]: *** [CMakeFiles/rippled.dir/build.make:551: CMakeFiles/rippled.dir/src/ripple/unity/rpcx.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:68: CMakeFiles/rippled.dir/all] Error 2
make: *** [Makefile:84: all] Error 2
>>> ERROR: rippled: all failed

On aarch64:

[ 90%] Building CXX object CMakeFiles/rippled.dir/src/ripple/unity/resource.cpp.o
[ 90%] Building C object CMakeFiles/rippled.dir/src/sqlite/sqlite_unity.c.o
In file included from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/impl/basic_fields.ipp:11:0,
                 from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/basic_fields.hpp:305,
                 from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/fields.hpp:12,
                 from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/message.hpp:12,
                 from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/empty_body.hpp:13,
                 from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/websocket/detail/decorator.hpp:11,
                 from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/websocket/option.hpp:13,
                 from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/ripple/server/Port.h:26,
                 from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/ripple/server/impl/Port.cpp:20,
                 from /home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/ripple/unity/server.cpp:27:
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp: In function 'int8_t beast::http::detail::unhex(char)':
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
     };
     ^
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/home/buildozer/aports/testing/rippled/src/rippled-0.70.1/src/beast/include/beast/http/detail/rfc7230.hpp:257:5: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
...

[ncopa]

I'm not sure why it does not happen on x86_64.