Split version into sane and excessive parts.

Split version into sane and excessive parts.

Upstream's version is 0.6.0.X, where X appears to be a large integer
in decimal that corresponds to a git sha1 has.  Such large numbers
violate the assumption, true with just about every previous package,
that version number components will fit in an int --- code that
handles version numbers does not use a multiprecision integer library
like gmp.  To address this, split the version into what would have
been the version under normal procedures (0.6.0), and put the bignum
into ${VERSION_EXCESSIVE}, allowing it be used in DISTNAME but not
PKGNAME.