include path for tcl.h

Hello all,

I'm working on a port of 6.5.1 for OpenBSD and it's mostly working. I want
to add the Tcl/Tk support but I can't figure out how to change the include
path for tcl.h from the default /usr/local/include to
/usr/local/include/tcl8.0 (as built by the tcl port).

Setting SRCH_INC in template/openbsd works but it's ugly because you'd get
a configure error even when you didn't want or have Tcl/Tk. I'd prefer if
it was conditional on something like USE_TCL, but the mechanics of
autoconf escape me.

The old 6.3.2 port in OpenBSD defined TCL_INCDIR (and the FAQ_Linux
mentions it also) but it doesn't seem to work any more and I can't find
any reference to it in src/interfaces/libpgtcl and src/pl/tcl.

What's the cleanest way of conditionally defining an extra include path?

Thanks
 --Louis  <louis@bertrandtech.on.ca>

Louis Bertrand       http://www.bertrandtech.on.ca
Bertrand Technical Services, Bowmanville, ON, Canada

OpenBSD: Secure by default.  http://www.openbsd.org/