build error against nettle 4

[ametzler]

Hello,

trying to build looking-glass against nettle4 triggered a failure:

cd /build/reproducible-path/looking-glass-0+b7+ds1/.build/client && /usr/bin/cmake -E cmake_depends "Unix Makefiles" /build/reproducible-path/looking-glass-0+b7+ds1/client /build/reproducible-path/looking-glass-0+b7+ds1/repos/cimgui /build/reproducible-path/looking-glass-0+b7+ds1/.build/client /build/reproducible-path/looking-glass-0+b7+ds1/.build/client/cimgui /build/reproducible-path/looking-glass-0+b7+ds1/.build/client/cimgui/CMakeFiles/cimgui.dir/DependInfo.cmake "--color=" cimgui
/build/reproducible-path/looking-glass-0+b7+ds1/repos/PureSpice/src/rsa.c: In function ‘sha1’:
/build/reproducible-path/looking-glass-0+b7+ds1/repos/PureSpice/src/rsa.c:48:23: error: passing argument 2 of ‘nettle_sha1_digest’ makes pointer from integer without a cast [-Wint-conversion]
   48 | #define SHA1_HASH_LEN 20
      |                       ^~
      |                       |
      |                       int
/build/reproducible-path/looking-glass-0+b7+ds1/repos/PureSpice/src/rsa.c:65:21: note: in expansion of macro ‘SHA1_HASH_LEN’
   65 |   sha1_digest(&ctx, SHA1_HASH_LEN, hash);
      |                     ^~~~~~~~~~~~~
compilation terminated due to -Wfatal-errors.
make[4]: *** [PureSpice/CMakeFiles/purespice.dir/build.make:110: PureSpice/CMakeFiles/purespice.dir/src/rsa.c.o] Error 1