lavd/opengl_enc: rename GL_RED_COMPONENT define

Rename GL_RED_COMPONENT into FF_GL_RED_COMPONENT
to explicity mark it is internal define, not OpenGL API.

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>
lavd/opengl_enc: factorize create/release window functions

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>
lavd/opengl_enc: factorize deinit_context function

This commit also fixes opengl deinitialization.
Program and shaders where not deleted.
Could impact MacOS implementation based on SDL window.

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>
lavd/opengl_enc: simplify opengl_load_procedures usage

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>
lavd/opengl_enc: fix window caption

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>
lavd/opengl_enc: remove inlines

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>