util: squashed clang fixes:

In file included from external/linux-tools-perf/builtin-annotate.c:28:
external/linux-tools-perf/util/evlist.h:29:19: error: field 'event_copy' with variable sized type 'union perf_event' not at the end of a struct or class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
        union perf_event event_copy;
                         ^
external/linux-tools-perf/util/evlist.h:76:39: error: duplicate 'const' declaration specifier [-Werror,-Wduplicate-decl-specifier]
bool perf_evlist__sample_id_all(const const struct perf_evlist *evlist);
                                      ^

external/linux-tools-perf/util/evsel.c:259:17: error: field 'map' with variable sized type 'struct cpu_map' not at the end of a struct or class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
        struct cpu_map map;
                       ^

external/linux-tools-perf/util/evsel.c:267:20: error: field 'map' with variable sized type 'struct thread_map' not at the end of a struct or class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
        struct thread_map map;
                          ^

external/linux-tools-perf/util/header.c:76:19: error: duplicate 'const' declaration specifier [-Werror,-Wduplicate-decl-specifier]
static const char const __perf_magic[9] __attribute__ ((aligned (8))) =
                  ^

external/linux-tools-perf/util/session.c:1168:16: error: comparison of constant 2 with expression of type 'enum map_type' is always true [-Werror,-Wtautological-constant-out-of-range-compare]
        for (i = 0; i < MAP__NR_TYPES; ++i) {
                    ~ ^ ~~~~~~~~~~~~~

external/linux-tools-perf/util/symbol.c:2282:22: error: comparison of constant 2 with expression of type
'enum map_type' is always true [-Werror,-Wtautological-constant-out-of-range-compare]
        for (type = 0; type < MAP__NR_TYPES; ++type) {
                       ~~~~ ^ ~~~~~~~~~~~~~

external/linux-tools-perf/util/symbol.c:2305:22: error: comparison of constant 2 with expression of type
'enum map_type' is always true [-Werror,-Wtautological-constant-out-of-range-compare]
        for (type = 0; type < MAP__NR_TYPES; ++type) {
                       ~~~~ ^ ~~~~~~~~~~~~~