perf tools: Check libunwind for availability of dwarf parsing feature

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: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Jean Pihet <jean.pihet@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>