Also add fstat() and lstat(). I don't #define the constants for
st_mode or d_type, but I provide enough to get the block size of a
file and to list the names in a directory. Some fields of struct stat
get truncated, see XXX in plat/osx/include/sys/stat.h.
In struct dirent, the inode field might be d_ino or d_fileno. I
picked d_ino because Apple's sys/dirent.h uses d_ino (but Apple's
manual pages use d_fileno).
Before this commit, the headers in plat/osx/include got installed
twice into PLATIND/osx386/include and PLATIND/osxppc/include. This
commit installs them once into PLATIND/osx/include and changes both
descr files to find them.
Several rules in lang/ depend on plat/osx386/include+headers or
plat/osxppc/include+headers. They each become a simplerule that
depends on plat/osx/include+headers.
