Revert "Android.rules: build x86 tests with -mstackrealign"

Starting with android ndk r15, clang much more tests are affected by the
-mstackrealign bugl (now nearly all functions are affected, and not just
the ones requiring 16-byte alignment). Due to their numbers, Xfailing
all of them is not a viable option, so we will just have to declare this
configuration unsupported, and wait until ndk ships a clang version that
has this bug fixed.

llvm-svn: 307252