[PATCH] perf build: Add missing cflags when building with custom libtraceevent

[Yicong Yang <yangyicong@huawei.com>]

From: Yicong Yang <yangyicong@hisilicon.com>

When building with custom libtraceevent, below errors occur:
$ make -C tools/perf NO_LIBPYTHON=1 PKG_CONFIG_PATH=<custom libtraceevent>
In file included from util/session.h:5,
                 from builtin-buildid-list.c:17:
util/trace-event.h:153:10: fatal error: traceevent/event-parse.h: No such file or directory
  153 | #include <traceevent/event-parse.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~
<snip similar errors of missing headers>

This is because the include path is missed in the cflags. Add it.

Fixes: 0f0e1f445690 ("perf build: Use pkg-config for feature check for libtrace{event,fs}")
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
Another problem occurs when building on my old Ubuntu 18.04.1 (4.15 kernel)
is that linux/mount.h (which is introduced in the later kernel version) is
missing. It's included in tools/include/uapi/linux/fs.h which header is
introduced recently. Does it make sense to have a copy of mount.h in tools/include?

 tools/perf/Makefile.config | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 4ddb27a48eed..53fc5f787a77 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -1194,7 +1194,7 @@ endif
 ifneq ($(NO_LIBTRACEEVENT),1)
   $(call feature_check,libtraceevent)
   ifeq ($(feature-libtraceevent), 1)
-    CFLAGS += -DHAVE_LIBTRACEEVENT
+    CFLAGS += -DHAVE_LIBTRACEEVENT $(shell $(PKG_CONFIG) --cflags libtraceevent)
     LDFLAGS += $(shell $(PKG_CONFIG) --libs-only-L libtraceevent)
     EXTLIBS += $(shell $(PKG_CONFIG) --libs-only-l libtraceevent)
     LIBTRACEEVENT_VERSION := $(shell $(PKG_CONFIG) --modversion libtraceevent).0.0
-- 
2.24.0