tools/latency: Use pkg-config in lib_setup of Makefile.config

This allows to build against libtraceevent and libtracefs installed
in non-standard locations.

Signed-off-by: Guilherme Amadio <amadio@gentoo.org>
Tested-by: Thorsten Leemhuis <linux@leemhuis.info>
Tested-by: Leo Yan <leo.yan@arm.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: linux-trace-devel@vger.kernel.org
Link: https://lore.kernel.org/r/20240717174739.186988-6-amadio@gentoo.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Author: amadio

tools/tracing/latency/Makefile.config

@@ -3,8 +3,9 @@
 STOP_ERROR :=
 
 define lib_setup
-  $(eval EXTLIBS += -l$(1))
   $(eval LIB_INCLUDES += $(shell sh -c "$(PKG_CONFIG) --cflags lib$(1)"))
+  $(eval LDFLAGS += $(shell sh -c "$(PKG_CONFIG) --libs-only-L lib$(1)"))
+  $(eval EXTLIBS += $(shell sh -c "$(PKG_CONFIG) --libs-only-l lib$(1)"))
 endef
 
 $(call feature_check,libtraceevent)