Always had that problem building under Debian sid amd64.
just add -l Xxf86vm to WXLIBS in makefile.unix
Well *snap*, that's what it was. Sometimes I get my virtual machines mixed up, thanks! Sending 10BTC to you!
For reference in case anyone else encounters this
WXLIBS= \
-l Xxf86vm \
-Wl,-Bstatic \
-l wx_gtk2ud-2.9 \
-Wl,-Bdynamic \
-l gtk-x11-2.0 -l SM