packages: missing propagation of !mmu from pango

A number of packages that select Pango (which depends on BR2_USE_MMU)
forget to also depends on BR2_USE_MMU. This commit fixes that.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>