perf build: Warn if libtracefs is not found

Signed-off-by: Guilherme Amadio <[email protected]>
Tested-by: Thorsten Leemhuis <[email protected]>
Tested-by: Leo Yan <[email protected]>
Acked-by: Steven Rostedt (Google) <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>

Author: amadio

tools/perf/Makefile.config

@@ -1206,6 +1206,8 @@ ifneq ($(NO_LIBTRACEEVENT),1)
     LIBTRACEFS_VERSION_3 := $(word 3, $(subst ., ,$(LIBTRACEFS_VERSION)))
     LIBTRACEFS_VERSION_CPP := $(shell expr $(LIBTRACEFS_VERSION_1) \* 255 \* 255 + $(LIBTRACEFS_VERSION_2) \* 255 + $(LIBTRACEFS_VERSION_3))
     CFLAGS += -DLIBTRACEFS_VERSION=$(LIBTRACEFS_VERSION_CPP)
+  else
+    $(warning libtracefs is missing. Please install libtracefs-dev/libtracefs-devel)
   endif
 endif