fix conflicting declaration compile error of GLDEBUGPROC with qt declaration
In my Qt 5.3.2 qopengl.h there are the following three declarations
#ifndef GL_ARB_debug_output
typedef void (APIENTRY *GLDEBUGPROCARB)(GLenum source,GLenum type,GLuint id,GLenum severity,GLsizei length,const GLchar *message,GLvoid *userParam);
#endif
#ifndef GL_AMD_debug_output
typedef void (APIENTRY *GLDEBUGPROCAMD)(GLuint id,GLenum category,GLenum severity,GLsizei length,const GLchar *message,GLvoid *userParam);
#endif
#ifndef GL_KHR_debug
typedef void (APIENTRY *GLDEBUGPROC)(GLenum source,GLenum type,GLuint id,GLenum severity,GLsizei length,const GLchar *message,GLvoid *userParam);
#endif
They conflict with the declarations in ACG/GL/gl-compat_4_4.hh, which are
typedef void (APIENTRY *GLDEBUGPROC)(GLenum source,GLenum type,GLuint id,GLenum severity,GLsizei length,const GLchar *message,const void *userParam);
typedef void (APIENTRY *GLDEBUGPROCARB)(GLenum source,GLenum type,GLuint id,GLenum severity,GLsizei length,const GLchar *message,const void *userParam);
typedef void (APIENTRY *GLDEBUGPROCAMD)(GLuint id,GLenum category,GLenum severity,GLsizei length,const GLchar *message,void *userParam);
due to the constness of the last parameter.
This patch fixes the compile error by removing const (and replacing void with GLvoid).