Stefan Fiedler:

package/base/tcl/tcl.conf

@@ -26,3 +26,5 @@ hook_add preconf 3 "cd unix"
 hook_add postinstall 3 'ln -vsf tclsh8.4 $bindir/tclsh'
 hook_add postinstall 3 "ln -vsf libtcl`tcl_libver $ver`.so $libdir/libtcl.so"
 
+# install headers required e.g. by itcl and brlcad
+hook_add postmake 3 "cp -a ../generic/tclInt.h ../generic/tclIntDecls.h $root/usr/include"

package/x11/tcltk/tcltk.conf

@@ -41,6 +41,9 @@ main_tcltk() {
 	ln -vsf tclsh8.4 $bindir/tclsh
 	ln -vsf libtcl$sver.so $libdir/libtcl.so
 
+	# install headers required e.g. by itcl and brlcad
+	cp -a ../generic/tclInt.h ../generic/tclIntDecls.h $root/usr/include
+
 	cd ../../tk$ver/unix
 	fix_doc tk
 	eval ./configure $confopt --enable-gcc --enable-shared