mesa: implement _mesa_GenVertexArrays() for GL_ARB_vertex_array_object

This also involves adding a gl_array_object::VBOonly field.  For the
ARB extension, all arrays in the object must reside in a VBO.  This flag
keeps track of that requirement.

src/mesa/main/arrayobj.h

@@ -74,6 +74,8 @@ void GLAPIENTRY _mesa_BindVertexArrayAPPLE( GLuint id );
 
 void GLAPIENTRY _mesa_DeleteVertexArraysAPPLE(GLsizei n, const GLuint *ids);
 
+void GLAPIENTRY _mesa_GenVertexArrays(GLsizei n, GLuint *arrays);
+
 void GLAPIENTRY _mesa_GenVertexArraysAPPLE(GLsizei n, GLuint *buffer);
 
 GLboolean GLAPIENTRY _mesa_IsVertexArrayAPPLE( GLuint id );