[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/matrix.h

@@ -0,0 +1,92 @@
+/* $Id: matrix.h,v 1.3 1997/04/20 16:18:15 brianp Exp $ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version:  2.3
+ * 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: matrix.h,v $
+ * Revision 1.3  1997/04/20 16:18:15  brianp
+ * added glOrtho and glFrustum API pointers
+ *
+ * Revision 1.2  1997/04/01 04:23:53  brianp
+ * added gl_analyze_*_matrix() functions
+ *
+ * Revision 1.1  1996/09/13 01:38:16  brianp
+ * Initial revision
+ *
+ */
+
+
+#ifndef MATRIX_H
+#define MATRIX_H
+
+
+#include "types.h"
+
+
+
+extern void gl_analyze_modelview_matrix( GLcontext *ctx );
+
+extern void gl_analyze_projection_matrix( GLcontext *ctx );
+
+extern void gl_analyze_texture_matrix( GLcontext *ctx );
+
+
+
+extern void gl_rotation_matrix( GLfloat angle, GLfloat x, GLfloat y, GLfloat z,
+                                GLfloat m[] );
+
+
+
+extern void gl_Frustum( GLcontext *ctx,
+                        GLdouble left, GLdouble right,
+                        GLdouble bottom, GLdouble top,
+                        GLdouble nearval, GLdouble farval );
+
+extern void gl_Ortho( GLcontext *ctx,
+                      GLdouble left, GLdouble right,
+                      GLdouble bottom, GLdouble top,
+                      GLdouble nearval, GLdouble farval );
+
+extern void gl_PushMatrix( GLcontext *ctx );
+
+extern void gl_PopMatrix( GLcontext *ctx );
+
+extern void gl_LoadIdentity( GLcontext *ctx );
+
+extern void gl_LoadMatrixf( GLcontext *ctx, const GLfloat *m );
+
+extern void gl_MatrixMode( GLcontext *ctx, GLenum mode );
+
+extern void gl_MultMatrixf( GLcontext *ctx, const GLfloat *m );
+
+extern void gl_Viewport( GLcontext *ctx,
+                         GLint x, GLint y, GLsizei width, GLsizei height );
+
+extern void gl_Rotatef( GLcontext *ctx,
+                        GLfloat angle, GLfloat x, GLfloat y, GLfloat z );
+
+extern void gl_Scalef( GLcontext *ctx, GLfloat x, GLfloat y, GLfloat z );
+
+extern void gl_Translatef( GLcontext *ctx, GLfloat x, GLfloat y, GLfloat z );
+
+
+#endif