Log Message:
Update Mesa and friends to latest version 5.0.2:

- fixed texgen problem causing texcoord's Q to be zero (stex3d)
- default GL_TEXTURE_COMPARE_MODE_ARB was wrong
- GL_CURRENT_MATRIX_NV query was wrong
- GL_CURRENT_MATRIX_STACK_DEPTH_NV query was off by one
- GL_LIST_MODE query wasn't correct
- GL_FOG_COORDINATE_SOURCE_EXT query wasn't supported
- GL_SECONDARY_COLOR_ARRAY_SIZE_EXT query returned wrong value
- blended, wide lines didn't always work correctly
- glVertexAttrib4svNV w component was always 1
- fixed bug in GL_IBM_rasterpos_clip (missing return)
- GL_DEPTH_TEXTURE_MODE = GL_ALPHA didn't work correctly
- a few Solaris compilation fixes
- fixed glClear() problem for DRI drivers (non-existant stencil, etc)
- fixed int/REAL mixup in GLU NURBS curve evaluator (Eric Cazeaux)
- fixed delete [] bug in SI GLU (bug 721765) (Diego Santa Cruz)
- glFog() didn't clamp fog colors
- fixed bad float/int conversion for GL_TEXTURE_PRIORITY in the
  gl[Get]TexParameteri[v] functions
  - fixed invalid memory references in glTexGen functions (bug 781602)
  - integer-valued color arrays weren't handled correctly
- glDrawPixels(GL_DEPTH_COMPONENT) with glPixelZoom didn't work
- GL_EXT_texture_lod_bias is part of 1.4, overlooked in 5.0.1
- build GLUT with -fexceptions so C++ apps propogate exceptions

While here, fix PR pkg/23003 by moving the version number to version.mk
and including that in the buildlink.