Reapply commit 6375238 against the new OpenGl_glext.h
Reapply commit 6375238 against the new OpenGl_glext.h

  GL extensions under hpux

  Under hpux some opengl extensions are predefined by hp opengl
  having different ID'S.

mathstuf/oce,heartvalve/oce,heartvalve/oce,tpaviot/oce,EvgeneOskin/oce,BenoitPerrot/oce,Tech-XCorp/oce,tpaviot/oce,finetjul/oce,heartvalve/oce,tpaviot/oce,mathstuf/oce,mathstuf/oce,finetjul/oce,Tridify/oce,tpaviot/oce,mathstuf/oce,Tech-XCorp/oce,heartvalve/oce,heartvalve/oce,Tech-XCorp/oce,finetjul/oce,finetjul/oce,Tech-XCorp/oce,BenoitPerrot/oce,EvgeneOskin/oce,BenoitPerrot/oce,EvgeneOskin/oce,Tech-XCorp/oce,Tridify/oce,Tridify/oce,tpaviot/oce,BenoitPerrot/oce,BenoitPerrot/oce,mathstuf/oce,finetjul/oce,EvgeneOskin/oce,Tridify/oce,EvgeneOskin/oce,Tridify/oce