Final update of the evening is that I'm now stuck getting it to recognise /opt/amiga/m68k-amigaos/lib/libpthread.a
Code:
checking for pthread_create in -lthr... no
checking for pthread_create in -lpthread... no
checking for pthread_create in -lpthreads... no
checking for pthread_create in -lc... no
checking for pthread_create in -lc_r... no
checking for pthread_create in -lroot... no
configure: WARNING: "Don't know how to find pthread library on your system -- thread support disabled"
have tried messing with LDFLAGS to be super clear about -lpthread but no joy. I think its bedtime :-)