I couldn't make it work with the old version so I went back to
the latest pkgsrc. This is with the latest cyrus packages and
INSTALL_UNSTRIPPED=YES in mk.conf:

ROOT www:/usr/pkgsrc/mail/cyrus-imapd22> gdb /usr/pkg/cyrus/bin/master 
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This GDB was configured as "i386--netbsdelf"...(no debugging symbols found)...
(gdb) run -d
Starting program: /usr/pkg/cyrus/bin/master -d
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...
Program received signal SIGUSR1, User defined signal 1.
0x48262ebf in __sigsuspend14 () from /usr/lib/libc.so.12
(gdb) bt
#0  0x48262ebf in __sigsuspend14 () from /usr/lib/libc.so.12
#1  0x4806c1b1 in __pth_mctx_set () from /usr/pkg/lib/libpthread.so.20
#2  0x4806f0c3 in pth_spawn () from /usr/pkg/lib/libpthread.so.20
#3  0x4806eae6 in pth__init () from /usr/pkg/lib/libpthread.so.20
#4  0x48074a03 in read () from /usr/pkg/lib/libpthread.so.20
#5  0x482a2236 in __sread () from /usr/lib/libc.so.12
#6  0x4829286a in __srefill () from /usr/lib/libc.so.12
#7  0x48286cda in fgets () from /usr/lib/libc.so.12
#8  0x804dcc7 in config_read_file ()
#9  0x804d192 in config_read ()
#10 0x804dd1d in masterconf_init ()
#11 0x804c3e3 in main ()
#12 0x8049720 in ___start ()