Change UnProject4 prototype to use nearVal and farVal instead of near

and far because Windows compiler can get confused over these old keywords.

include/GL/glu.h

@@ -314,7 +314,7 @@ GLAPI void GLAPIENTRY gluTessNormal (GLUtesselator* tess, GLdouble valueX, GLdou
 GLAPI void GLAPIENTRY gluTessProperty (GLUtesselator* tess, GLenum which, GLdouble data);
 GLAPI void GLAPIENTRY gluTessVertex (GLUtesselator* tess, GLdouble *location, GLvoid* data);
 GLAPI GLint GLAPIENTRY gluUnProject (GLdouble winX, GLdouble winY, GLdouble winZ, const GLdouble *model, const GLdouble *proj, const GLint *view, GLdouble* objX, GLdouble* objY, GLdouble* objZ);
-GLAPI GLint GLAPIENTRY gluUnProject4 (GLdouble winX, GLdouble winY, GLdouble winZ, GLdouble clipW, const GLdouble *model, const GLdouble *proj, const GLint *view, GLdouble near, GLdouble far, GLdouble* objX, GLdouble* objY, GLdouble* objZ, GLdouble* objW);
+GLAPI GLint GLAPIENTRY gluUnProject4 (GLdouble winX, GLdouble winY, GLdouble winZ, GLdouble clipW, const GLdouble *model, const GLdouble *proj, const GLint *view, GLdouble nearVal, GLdouble farVal, GLdouble* objX, GLdouble* objY, GLdouble* objZ, GLdouble* objW);
 
 #ifdef __cplusplus
 }