Decode hex digits from __SUNPRO_C and __SUNPRO_CC to compute the version
number components.  Note that the constant encodes decimal digits as hex
digits (never larger than 9).  We represent them as decimal after
extraction.  See documentation at

  http://predef.sourceforge.net/precomp.html

Although the documented version number format is

  0xVRP where V = Version, R = Revision, P = Patch

it holds only though SunPro C/C++ version 5.9.  Later versions have
a two-digit revision (minor) number so their format is 0xVRRP.