arm-unknown-linux-gnueabihf was incorrectly used as llvm-target instead
of armv7-unknown-linux-gnueabihf when building for some Cortex A SoCs.
This may cause segfaults in non trivial rust applications on ARMv7
when e.g. +a7 is passed to LLVM. It seems to differ between different
versions of the compiler and LLVM versions.