Fewer macros in tar.h

Fewer macros in tar.h

* src/tar.h (REGTYPE, AREGTYPE, SYMTYPE, BLKTYPE, FIFOTYPE)
(XHDTYPE, XGLTYPE, TSUID, TSGID, TSVTX, TUREAD, TUWRITE, TUEXEC)
(TGREAD, TGWRITE, TGEXEC, TOREAD, TOWRITE, TOEXEC)
(SPARSES_IN_EXTRA_HEADER, SPARSES_IN_OLDGNU_HEADER)
(SPARSES_IN_SPARSE_HEADER, GNUTYPE_DUMPDIR, GNUTYPE_LONGLINK)
(GNUTYPE_LONGNAME, GNUTYPE_MULTIVOL, GNUTYPE_SPARSE)
(GNUTYPE_VOLHDR, SOLARIS_XHDTYPE, SPARSES_IN_STAR_HEADER)
(SPARSES_IN_STAR_EXT_HEADER, BLOCKSIZE):
Now constants, not macros.