Increment the version number to 1.7.0.

Increment the minor verison number since libglvnd has added support for
Haiku.

Increment the version number to 1.6.0.

Increment the version number to 1.5.0.

Increment the minor version, since we added some features that other
things might depend on.

Increment version number to 1.4.0.

Increment the minor version this time, since we've extended the EGL
vendor library interface.

libglvnd-1.3.4

libglvnd-1.3.3

libglvnd-1.3.2

libglvnd-1.3.1

libglvnd-1.3.0

Bump the version number to 1.2.0.