[PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized

[Arnaldo Carvalho de Melo]

In some older distros the build is failing due to
-Werror=maybe-uninitialized, in this case we know that this isn't the
case because 'arch' gets initialized by evsel__get_arch(), so just init
it to NULL to silence those cases.

E.g.:

    32    17.12 opensuse:15.5                 : FAIL gcc version 7.5.0 (SUSE Linux)
        util/annotate.c: In function 'hist_entry__get_data_type':
    util/annotate.c:2269:15: error: 'arch' may be used uninitialized in this function [-Werror=maybe-uninitialized]
      struct arch *arch;
                   ^~~~
    cc1: all warnings being treated as errors

      43     7.30 ubuntu:18.04-x-powerpc64el    : FAIL gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
    util/annotate.c: In function 'hist_entry__get_data_type':
    util/annotate.c:2351:36: error: 'arch' may be used uninitialized in this function [-Werror=maybe-uninitialized]
       if (map__dso(ms->map)->kernel && arch__is(arch, "x86") &&
                                        ^~~~~~~~~~~~~~~~~~~~~
    cc1: all warnings being treated as errors

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/annotate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index b795f27f26024f35..f316e0b65897957a 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -2266,7 +2266,7 @@ struct annotated_data_type *hist_entry__get_data_type(struct hist_entry *he)
 {
 	struct map_symbol *ms = &he->ms;
 	struct evsel *evsel = hists_to_evsel(he->hists);
-	struct arch *arch;
+	struct arch *arch = NULL;
 	struct disasm_line *dl;
 	struct annotated_insn_loc loc;
 	struct annotated_op_loc *op_loc;
-- 
2.44.0