perf build: Move feature checks code under tools/build

Moving feature checks code under tools/build directory.

Changing also $feature_dir to point to new feature directory location
and perf Makefiles to include Makefile.feature from new location.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <david.ahern@oracle.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-3lamtb30dhf4wo99y1n8kxg0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/build/feature/test-libunwind-debug-frame.c

@@ -0,0 +1,16 @@
+#include <libunwind.h>
+#include <stdlib.h>
+
+extern int
+UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,
+				 unw_word_t ip, unw_word_t segbase,
+				 const char *obj_name, unw_word_t start,
+				 unw_word_t end);
+
+#define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)
+
+int main(void)
+{
+	dwarf_find_debug_frame(0, NULL, 0, 0, NULL, 0, 0);
+	return 0;
+}