The newly added dwarf unwinding feature [1] requires:
. a recent version (>= 1.1) of libunwind,
. libunwind to be configured with --enable-debug-frame.

[1] http://www.spinics.net/lists/kernel/msg1598951.html

Add the corresponding API tests in the feature check list.
Acked-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NJean Pihet <jean.pihet@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>