perf evsel: Move xyarray.h from evsel.c to evsel.h to reduce include dep tree

All we need in util/evsel.h is the foward declaration of 'struct
xyarray', not the internal/xyarray.h, that can be moved to util/evsel.c
and then we reduce the header dependency tree.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-wwqce6ixwcyq6yzx3ljrdm80@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/evsel.c

@@ -39,6 +39,7 @@
 #include "string2.h"
 #include "memswap.h"
 #include "util/parse-branch-options.h"
+#include <internal/xyarray.h>
 
 #include <linux/ctype.h>
 

tools/perf/util/evsel.h

@@ -8,7 +8,6 @@
 #include <linux/perf_event.h>
 #include <linux/types.h>
 #include <internal/evsel.h>
-#include <internal/xyarray.h>
 #include "symbol_conf.h"
 #include "cpumap.h"
 #include "counts.h"
@@ -93,6 +92,7 @@ enum perf_tool_event {
 };
 
 struct bpf_object;
+struct xyarray;
 
 /** struct evsel - event selector
  *