OK, committed the fixes to tcl and tk.

Unfortunately, anything that tries to link against tcl is still going 
to run into problems with its dependencies (-lpthread, etc). The 
dependency info is in the installed tclConfig.sh, and it seems like the 
right thing to do would be to extract it into tcl's buildlink3.mk 
somehow for other packages to use. But the best I could come up with 
was:

TCL_DEPLIBS?= ${TCLCONFIG_SH:!(cat ${TCLCONFIG_SH}; echo eval echo 
'\$TCL_LIBS') | ${SH}!}

but I'm sure there must be a better way. (We could also just hack each 
package's configure script to source tclConfig.sh, but that seems like 
a lot of work.)

-- Dan