Bug#886264: firefox-esr: FTBFS on ppc64el

[Julian Gilbey]

Package: firefox-esr
Version: 52.5.3esr-1

This is the second version of firefox-esr in a row which has a
build-failure on ppc64el, meaning that this package cannot migrate to
testing.  There was a security fix in 52.5.2esr-1, so it would be very
good to attempt to address this.

Sadly, I don't have any idea how the firefox build works or what might
be causing the problem, so I don't know how to help fix this one.

Best wishes,

   Julian