perf tests bp_account: Add dedicated checking helper is_supported()

perf tests bp_account: Add dedicated checking helper is_supported()

The arm architecture supports breakpoint accounting but it doesn't
support breakpoint overflow signal handling.  The current code uses the
same checking helper, thus it disables both testings (bp_account and
bp_signal) for arm platform.

For handling two testings separately, this patch adds a dedicated
checking helper is_supported() for breakpoint accounting testing, thus
it allows supporting breakpoint accounting testing on arm platform; the
old helper test__bp_signal_is_supported() is only used to checking for
breakpoint overflow signal testing.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Brajeswar Ghosh <brajeswar.linux@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Will Deacon <will@kernel.org>
Link: http://lore.kernel.org/lkml/20191018085531.6348-2-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>