This cuts about 3 MiB from the installed size. On Linux, the configure
script is supposed to detect that installing tzdata is unnecessary,
but it looks in locations like /usr/share/zoneinfo.
This reduces tcl's total size from 25.0 MiB to 8.6 MiB. Admittedly
this is also because putting the manpages in the right place causes
all man3 pages to be deleted by the multiple outputs setup hook. Not
sure if that's desirable behaviour...
