package/glm: bump to version 0.9.9.4

- Disable tests as they are enabled by default since version 0.9.9.1:
  https://github.com/g-truc/glm/commit/d307d390193f4027faec48ac79d7f74b2bec6e56
- Static and shared libraries are always built since version 0.9.9.1:
  https://github.com/g-truc/glm/commit/a23dd2f800185a5e233534fed82fc5c2840fbe5c
  So, disable them as GLM is header-only (it should be noted that
  upstream wants to keep those libraries as the commit to disable them
  has been reverted:
  https://github.com/g-truc/glm/commit/ca8372490eb8742d402878c9e930b891225982e6
- Add hash for license file (now in manual.md#section0)

Fixes:
 - http://autobuild.buildroot.org/results/3cf1fd3387bd4952470edcfcb93d44f58c9e7ff7



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>