Help with pkgsrc configuration

OK, I learned from my last post to look closer, try some things, and try 
to work out what's going on for myself.

Well, this one is beyond my skill level, it seems.

I'm trying to build samba4 to run on my Mac G3.  My build system is 
Debian Gnu/Linux 10.7, set up per the instructions in 
pkgsrc/doc/HOWTO-use-crosscompile.

When samba4 failed, I tried some other packages, all of which fail at 
some point.  But some cross compiles appear to work, for example in 
pkgsrc/packages.powerpc/All there is a libhfs-3.2.6nb2.tgz file, after 
running 'bmake package' in pkgsrc/sysutils/hfsutils.

However, most of the compiles (hfsutils in this case) fail quickly with 
link errors such as:

/usr/bin/ld: 
/home/rmcgowan/src/netbsd/usr/pkgsrc/sysutils/hfsutils/work.powerpc/.buildlink/lib/libhfs.a(volume.o): 
\
         in function `v_readvbm':
(.text+0x62a): undefined reference to `__errno'
/usr/bin/ld: (.text+0x642): undefined reference to `__errno'
/usr/bin/ld: 
/home/rmcgowan/src/netbsd/usr/pkgsrc/sysutils/hfsutils/work.powerpc/.buildlink/lib/libhfs.a(volume.o): 
\
         in function `v_getthread':

Working through the file I captured from the bmake, I found for 
hfsutils, the following items were the primary errors:

     undefined reference to `__ctime50'
     undefined reference to `__errno'
     undefined reference to `__gmtime50'
     undefined reference to `__locatime50'
     undefined reference to `__mktime50'
     undefined reference to `__sF'
     undefined reference to `__srget'
     undefined reference to `__stat50'
     undefined reference to `__swbuf'
     undefined reference to `_ctype_tab_'
     undefined reference to `_tolower_tab_'

In a few other cases, it is a missing include file.  For example, I 
tried building libgee, and it quit with the following:

/usr/include/x86_64-linux-gnu/c++/8/bits/os_defines.h:39:10: fatal 
error: features.h: No such file or directory
  #include <features.h>
               ^~~~~~~~~~~~

Note that os_defines.h is found in the system include /usr/include/... 
but that features.h, which is present in the system directory 
/usr/include, isn't found.

Based on the above I have to assume I've missed something in the 
configuration or setup of pkgsrc for cross compiling.

Any help much appreciated.

Bob