Re: gnunet build fails (Slackware)

Thanks Martin, upgrading and using llvm did the trick.

There is another problem now.

```
[683/1092] Linking target src/service/zonemaster/gnunet-service-zonemaster
FAILED: src/service/zonemaster/gnunet-service-zonemaster
cc  -o src/service/zonemaster/gnunet-service-zonemaster 
src/service/zonemaster/gnunet-service-zonemaster.p/gnunet-service-zonemaster.c.o 
-Wl,--as-needed -Wl,--no-undefined -Wl,--unresolved-symbols=report-all 
'-Wl,-rpath,$ORIGIN/../../lib/util:$ORIGIN/../dht:$ORIGIN/../identity:$ORIGIN/../statistics:$ORIGIN/../namecache:$ORIGIN/../../lib/gnsrecord:$ORIGIN/../namestore' 
-Wl,-rpath-link,/home/cypher/src/git.gnunet.org/gnunet/builddir/src/lib/util 
-Wl,-rpath-link,/home/cypher/src/git.gnunet.org/gnunet/builddir/src/service/dht 
-Wl,-rpath-link,/home/cypher/src/git.gnunet.org/gnunet/builddir/src/service/identity 
-Wl,-rpath-link,/home/cypher/src/git.gnunet.org/gnunet/builddir/src/service/statistics 
-Wl,-rpath-link,/home/cypher/src/git.gnunet.org/gnunet/builddir/src/service/namecache 
-Wl,-rpath-link,/home/cypher/src/git.gnunet.org/gnunet/builddir/src/lib/gnsrecord 
-Wl,-rpath-link,/home/cypher/src/git.gnunet.org/gnunet/builddir/src/service/namestore 
-Wl,--start-group src/lib/util/libgnunetutil.so.15.0.0 
src/service/dht/libgnunetdht.so.4.0.0 
src/service/identity/libgnunetidentity.so.1.0.0 
src/service/statistics/libgnunetstatistics.so.2.0.0 
src/service/namecache/libgnunetnamecache.so.0.0.0 
src/service/namestore/libgnunetnamestore.so.0.0.1 
src/lib/gnsrecord/libgnunetgnsrecord.so.0.0.0 -Wl,--end-group
/usr/bin/ld: 
src/service/zonemaster/gnunet-service-zonemaster.p/gnunet-service-zonemaster.c.o: 
undefined reference to symbol 'pthread_create@@GLIBC_2.2.5'
/usr/bin/ld: /lib64/libpthread.so.0: error adding symbols: DSO missing 
from command line
collect2: error: ld returned 1 exit status
[684/1092] Generating symbol file 
src/service/gns/libgnunetgns.so.0.0.0.p/libgnunetgns.so.0.0.0.symbols

```

It looks like '-lpthread' is missing and is a requirement for systems 
using glibc < 2.34 
(https://developers.redhat.com/articles/2021/12/17/why-glibc-234-removed-libpthread).