perf tools: Add file-handle feature test

The file handle (FHANDLE) support is configurable so some systems might not
have it. So add a config feature item to check it on build time so that we
don't add the cgroup tracking feature based on that.

Committer notes:

Had to make the test use the same construct as its later use in
synthetic-events.c, in the next patch in this series. i.e. make it be:

struct {
struct file_handle fh;
uint64_t cgroup_id;
} handle;

To cope with:

CC /tmp/build/perf/util/cloexec.o
util/synthetic-events.c:428:22: error: field 'fh' with CC /tmp/build/perf/util/call-path.o
variable sized type 'struct file_handle' not at the end of a struct or class is a GNU
extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
struct file_handle fh;
^
1 error generated.

Deal with this at some point, i.e. investigate if the right thing is to
remove that -Wgnu-variable-sized-type-not-at-end from our CFLAGS, for
now do the test the same way as it is used looks more sensible.

Reported-by: Arnaldo Carvalho de Melo <[e-mail]>
Signed-off-by: Namhyung Kim <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
[ split from a larger patch, removed blank line at EOF ]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/build/Makefile.feature

···
         setns				\
         libaio				\
         libzstd				\
-        disassembler-four-args
+        disassembler-four-args		\
+        file-handle
 
 # FEATURE_TESTS_BASIC + FEATURE_TESTS_EXTRA is the complete list
 # of all feature tests

tools/build/feature/Makefile

···
          test-llvm.bin				\
          test-llvm-version.bin			\
          test-libaio.bin			\
-         test-libzstd.bin
+         test-libzstd.bin			\
+         test-file-handle.bin
 
 FILES := $(addprefix $(OUTPUT),$(FILES))
 
···
 
 $(OUTPUT)test-libzstd.bin:
 	$(BUILD) -lzstd
+
+$(OUTPUT)test-file-handle.bin:
+	$(BUILD)
 
 ###############################
 

tools/build/feature/test-file-handle.c

···
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <inttypes.h>
+
+int main(void)
+{
+	struct {
+		struct file_handle fh;
+		uint64_t cgroup_id;
+	} handle;
+	int mount_id;
+
+	name_to_handle_at(AT_FDCWD, "/", &handle.fh, &mount_id, 0);
+	return 0;
+}

tools/perf/Makefile.config

···
   CFLAGS += -DHAVE_GETTID
 endif
 
+ifeq ($(feature-file-handle), 1)
+  CFLAGS += -DHAVE_FILE_HANDLE
+endif
+
 ifdef NO_LIBELF
   NO_DWARF := 1
   NO_DEMANGLE := 1