Installworld and /usr/include/*.h modification times

[Kimmo Paasiala]

Hello list,

Why are /usr/include files installed with "install -C" during "make
installworld"  when almost everything else is installed without the -C
flag? This makes it harder to track which files were actually
installed during the last "make installworld". One can easily find
obsolete files  (that are not covered with make delete-old(-libs))
with "find -x / -type f -mtime +suitable_time" but this doesn't work
for /usr/include files because the modification times are not bumped
on "make installworld".