When libbpf is present the build uses definitions in libbpf hashmap.c,
however, libbpf's hashmap.h wasn't being used. Switch to using the
correct hashmap.h dependent on the define HAVE_LIBBPF_SUPPORT. This was
the original intent in:

  https://lore.kernel.org/lkml/20200515221732.44078-8-irogers@google.com/Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20220824050604.352156-1-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>