GL_EXT_semaphore
http://www.opengl.org/registry/specs/EXT/external_objects.txt
GL_EXT_semaphore

	GL_LAYOUT_GENERAL_EXT 0x958D
	GL_LAYOUT_COLOR_ATTACHMENT_EXT 0x958E
	GL_LAYOUT_DEPTH_STENCIL_ATTACHMENT_EXT 0x958F
	GL_LAYOUT_DEPTH_STENCIL_READ_ONLY_EXT 0x9590
	GL_LAYOUT_SHADER_READ_ONLY_EXT 0x9591
	GL_LAYOUT_TRANSFER_SRC_EXT 0x9592
	GL_LAYOUT_TRANSFER_DST_EXT 0x9593
	GL_LAYOUT_DEPTH_READ_ONLY_STENCIL_ATTACHMENT_EXT 0x9530
	GL_LAYOUT_DEPTH_ATTACHMENT_STENCIL_READ_ONLY_EXT 0x9531

	void glDeleteSemaphoresEXT (GLsizei n, const GLuint* semaphores)
	void glGenSemaphoresEXT (GLsizei n, GLuint* semaphores)
	void glGetSemaphoreParameterui64vEXT (GLuint semaphore, GLenum pname, GLuint64* params)
	GLboolean glIsSemaphoreEXT (GLuint semaphore)
	void glSemaphoreParameterui64vEXT (GLuint semaphore, GLenum pname, const GLuint64* params)
	void glSignalSemaphoreEXT (GLuint semaphore, GLuint numBufferBarriers, const GLuint* buffers, GLuint numTextureBarriers, const GLuint *textures, const GLenum *dstLayouts)
	void glWaitSemaphoreEXT (GLuint semaphore, GLuint numBufferBarriers, const GLuint* buffers, GLuint numTextureBarriers, const GLuint *textures, const GLenum *srcLayouts)