package/solarus: bump to version 1.6.4

Add glm dependency since the bundled version is gone [1].

Update indentation of hash file (two spaces).

[1] https://gitlab.com/solarus-games/solarus/commit/5285c8e1afa538bbcd4c8654f9bbfb270cc7f52



Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>