GL_COMPRESSED_RGBA_S3TC_DXT3_EXT constants missing?

[Pixel-Hellmin]

I can't seem to find:
GL_COMPRESSED_RGBA_S3TC_DXT1_EXT
GL_COMPRESSED_RGBA_S3TC_DXT3_EXT
GL_COMPRESSED_RGBA_S3TC_DXT5_EXT

are these missing?

[fayalalebrun]

If you want to use extensions, you need to use gl_generator directly: https://crates.io/crates/gl_generator