The target was added for Unix toolchains in #901, but a later pull #1891 added
it again. Since clang only uses the last target flag that's passed in, all
customization done for the first one was unused these last 4+ years, so remove
it and change tests that look for custom strings passed by the first one.
Currently we only support building for android armv7, arm64, x86,
x86_64. In the future, if support for MIPS and MIPS64 is added, we
should normalise those as well. This is needed to support compilation
against modern NDKs.
