Set the default number of samples per pixel to 4 and actually use the value set

Set the default number of samples per pixel to 4 and actually use the value set
with glutSetOption(GLUT_MULTISAMPLE,...) in Windows code. Previously the Windows
code used a hardwired value of 4 and the GLX code had a default of 0, neither
made much sense. Similarly, set the default number of auxiliary buffers to 1 and
use that value when GLUT_AUX is used. Note: There latter token has the same
value as GLUT_AUX1, and for historical reasons we seem to have 2 APIs to set the
number of auxiliary buffers: Explicitly using GLUT_AUX1 ... GLUT_AUX4, and using
a combination of GLUT_AUX with glutSetOption. The default of 1 ensures
consistent behaviour in both cases.

git-svn-id: svn+ssh://svn.code.sf.net/p/freeglut/code/trunk/freeglut/freeglut@802 7f0cb862-5218-0410-a997-914c9d46530a