* Fix build on armhf by disabling unaligned FP accesses emulation
  - add debian/patches/armhf-disable-unaligned-fp-access-emulation.patch
* Reduce the memory used by the linking process on armhf, to work around build failures on launchpad
  - add debian/patches/armhf-reduce-linker-memory-use.patch
* Build with clang
  - update debian/config/mozconfig.in
  - update debian/control{,.in}
  - add debian/patches/armhf-clang-no-integrated-as-for-neon.patch
  - add debian/patches/ppc64el-workaround-bug-1555531.patch
  - add debian/patches/s390x-fix-hidden-symbol.patch