[ndk][backport] Fix a problem where the AArch64 ELF assembler.

Fix a problem where the AArch64 ELF assembler was failing with
-no-exec-stack. This was due to it not deriving from the correct asm
info base class and missing the override for the exec stack section
query. Added another line to the noexec test line to make sure this
doesn't regress.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227074 91177308-0d34-0410-b5e6-96231b3b80d8