Hi all,

A bug in the target attribute parsing logic led to us silently accepting attribute strings
that did not appear in the attributes table i.e invalid attributes.

This patch fixes that oversight so we now error out on obviously bogus strings.

Bootstrapped and tested on aarch64.

Ok for trunk?

Thanks,
Kyrill

2016-01-15  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

     * config/aarch64/aarch64.c (aarch64_process_one_target_attr): Return
     false when argument string is not found in the attributes table
     at all.

2016-01-15  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

     * gcc.target/aarch64/target_attr_17.c: New test.