[OPENGL32][MESA] Downgrade Mesa library to version 2.6

With this commit, we now use a forked version of MESA which only supports OpenGL 1.1, like the windows implementation does.
It exposes :
  - The same pixel formats
  - The same set of extensions
  - Nothing more
All of this without taking 10% of your build time.
If you need a more modern option, look at the MESA package from Rapps, which is (and must be) maintained outside of this code tree.
CORE-7499

dll/opengl/mesa/vb.h

@@ -0,0 +1,158 @@
+/* $Id: vb.h,v 1.12 1997/08/13 02:07:17 brianp Exp $ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version:  2.4
+ * Copyright (C) 1995-1997  Brian Paul
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the Free
+ * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+/*
+ * $Log: vb.h,v $
+ * Revision 1.12  1997/08/13 02:07:17  brianp
+ * set VB_MAX to 72 is using Glide for better performance (David Bucciarelli)
+ *
+ * Revision 1.11  1997/06/21 21:30:59  brianp
+ * updated many comments
+ *
+ * Revision 1.10  1997/06/20 02:08:23  brianp
+ * changed color components from GLfixed to GLubyte
+ *
+ * Revision 1.9  1997/05/09 22:41:55  brianp
+ * replaced gl_init_vb() with gl_alloc_vb()
+ *
+ * Revision 1.8  1997/04/24 00:29:36  brianp
+ * added TexCoordSize
+ *
+ * Revision 1.7  1997/04/20 15:59:30  brianp
+ * removed VERTEX2_BIT stuff
+ *
+ * Revision 1.6  1997/04/12 16:21:35  brianp
+ * added CLIP_* flags and gl_init_vb()
+ *
+ * Revision 1.5  1997/04/07 02:59:59  brianp
+ * added VertexSizeMask
+ *
+ * Revision 1.4  1997/04/02 03:13:12  brianp
+ * removed Unclipped[], added ClipMask[], ClipOrMask, ClipAndMask
+ *
+ * Revision 1.3  1996/12/18 19:59:44  brianp
+ * removed the material bitmask constants
+ *
+ * Revision 1.2  1996/09/27 01:31:17  brianp
+ * added gl_init_vb() prototype
+ *
+ * Revision 1.1  1996/09/13 01:38:16  brianp
+ * Initial revision
+ *
+ */
+
+
+/*
+ * OVERVIEW:  The vertices defined between glBegin() and glEnd()
+ * are accumulated in the vertex buffer.  When either the
+ * vertex buffer becomes filled or glEnd() is called, we must flush
+ * the buffer.  That is, we apply the vertex transformations, compute
+ * lighting, fog, texture coordinates etc.  Then, we can render the
+ * vertices as points, lines or polygons by calling the gl_render_vb()
+ * function in render.c
+ *
+ */
+
+
+#ifndef VB_H
+#define VB_H
+
+
+#include "types.h"
+
+
+
+/* Flush VB when this number of vertices is accumulated:  (a multiple of 12) */
+#define VB_MAX 480
+
+/* Arrays must also accomodate new vertices from clipping: */
+#define VB_SIZE  (VB_MAX + 2 * (6 + MAX_CLIP_PLANES))
+
+
+/* Bit values for VertexSizeMask, below. */
+/*#define VERTEX2_BIT  1*/
+#define VERTEX3_BIT  2
+#define VERTEX4_BIT  4
+
+
+
+struct vertex_buffer {
+   GLfloat Obj[VB_SIZE][4];	/* Object coords */
+   GLfloat Eye[VB_SIZE][4];	/* Eye coords */
+   GLfloat Clip[VB_SIZE][4];	/* Clip coords */
+   GLfloat Win[VB_SIZE][3];	/* Window coords */
+
+   GLfloat Normal[VB_SIZE][3];	/* Normal vectors */
+
+   GLubyte Fcolor[VB_SIZE][4];	/* Front colors (RGBA) */
+   GLubyte Bcolor[VB_SIZE][4];	/* Back colors (RGBA) */
+   GLubyte (*Color)[4];		/* == Fcolor or Bcolor */
+
+   GLuint Findex[VB_SIZE];	/* Front color indexes */
+   GLuint Bindex[VB_SIZE];	/* Back color indexes */
+   GLuint *Index;		/* == Findex or Bindex */
+
+   GLboolean Edgeflag[VB_SIZE];	/* Polygon edge flags */
+
+   GLfloat TexCoord[VB_SIZE][4];/* Texture coords */
+
+   GLubyte ClipMask[VB_SIZE];	/* bitwise-OR of CLIP_* values, below */
+   GLubyte ClipOrMask;		/* bitwise-OR of all ClipMask[] values */
+   GLubyte ClipAndMask;		/* bitwise-AND of all ClipMask[] values */
+
+   GLuint Start;		/* First vertex to process */
+   GLuint Count;		/* Number of vertexes in buffer */
+   GLuint Free;			/* Next empty position for clipping */
+
+   GLuint VertexSizeMask;	/* Bitwise-or of VERTEX[234]_BIT */
+   GLuint TexCoordSize;		/* Either 2 or 4 */
+   GLboolean MonoColor;		/* Do all vertices have same color? */
+   GLboolean MonoNormal;	/* Do all vertices have same normal? */
+   GLboolean MonoMaterial;	/* Do all vertices have same material? */
+
+   /* to handle glMaterial calls inside glBegin/glEnd: */
+   GLuint MaterialMask[VB_SIZE];	/* Which material values to change */
+   struct gl_material Material[VB_SIZE][2]; /* New material values */
+};
+
+
+
+/* Vertex buffer clipping flags */
+#define CLIP_RIGHT_BIT   0x01
+#define CLIP_LEFT_BIT    0x02
+#define CLIP_TOP_BIT     0x04
+#define CLIP_BOTTOM_BIT  0x08
+#define CLIP_NEAR_BIT    0x10
+#define CLIP_FAR_BIT     0x20
+#define CLIP_USER_BIT    0x40
+#define CLIP_ALL_BITS    0x3f
+
+#define CLIP_ALL   1
+#define CLIP_NONE  2
+#define CLIP_SOME  3
+
+
+extern struct vertex_buffer *gl_alloc_vb(void);
+
+
+#endif