This commit related to the dynamic creation of data that is used
to parse commands and options via Lookup.
windows/windows.h: Lookup() constify call-site
tcltk/tclmagic.c: Lookup() constify call-site
graphics/W3Dmain.c: Lookup() constify call-site
windows/windSend.c: Lookup() constify call-site
windows/windMain.c: Lookup() constify call-site
windows/windInt.h: Lookup() constify call-site
textio/txMain.c: Lookup() constify call-site