tools: Make pkg-config dependency checks usable by other tools

Other tools, in tools/verification and tools/tracing, make use of
libtraceevent and libtracefs as dependencies. This allows setting
up the feature check flags for them as well.
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/20240717174739.186988-3-amadio@gentoo.orgSigned-off-by: Namhyung Kim <namhyung@kernel.org>

tools/build/Makefile.feature

@@ -149,6 +149,24 @@ FEATURE_DISPLAY ?=              \
 #
 FEATURE_GROUP_MEMBERS-libbfd = libbfd-liberty libbfd-liberty-z
 
+#
+# Declare list of feature dependency packages that provide pkg-config files.
+#
+FEATURE_PKG_CONFIG ?=           \
+         libtraceevent          \
+         libtracefs
+
+feature_pkg_config = $(eval $(feature_pkg_config_code))
+define feature_pkg_config_code
+  FEATURE_CHECK_CFLAGS-$(1) := $(shell $(PKG_CONFIG) --cflags $(1) 2>/dev/null)
+  FEATURE_CHECK_LDFLAGS-$(1) := $(shell $(PKG_CONFIG) --libs $(1) 2>/dev/null)
+endef
+
+# Set FEATURE_CHECK_(C|LD)FLAGS-$(package) for packages using pkg-config.
+ifneq ($(PKG_CONFIG),)
+  $(foreach package,$(FEATURE_PKG_CONFIG),$(call feature_pkg_config,$(package)))
+endif
+
 # Set FEATURE_CHECK_(C|LD)FLAGS-all for all FEATURE_TESTS features.
 # If in the future we need per-feature checks/flags for features not
 # mentioned in this list we need to refactor this ;-).

tools/perf/Makefile.config

@@ -182,20 +182,15 @@ endif
 FEATURE_CHECK_CFLAGS-libzstd := $(LIBZSTD_CFLAGS)
 FEATURE_CHECK_LDFLAGS-libzstd := $(LIBZSTD_LDFLAGS)
 
+# for linking with debug library, run like:
+# make DEBUG=1 PKG_CONFIG_PATH=/opt/libtraceevent/(lib|lib64)/pkgconfig
+
 ifneq ($(NO_LIBTRACEEVENT),1)
   ifeq ($(call get-executable,$(PKG_CONFIG)),)
     $(error Error: $(PKG_CONFIG) needed by libtraceevent is missing on this system, please install it)
   endif
 endif
 
-# for linking with debug library, run like:
-# make DEBUG=1 PKG_CONFIG_PATH=/opt/libtraceevent/(lib|lib64)/pkgconfig
-FEATURE_CHECK_CFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --cflags libtraceevent 2>/dev/null)
-FEATURE_CHECK_LDFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --libs libtraceevent 2>/dev/null)
-
-FEATURE_CHECK_CFLAGS-libtracefs := $(shell $(PKG_CONFIG) --cflags libtracefs 2>/dev/null)
-FEATURE_CHECK_LDFLAGS-libtracefs := $(shell $(PKG_CONFIG) --libs libtracefs 2>/dev/null)
-
 FEATURE_CHECK_CFLAGS-bpf = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(SRCARCH)/include/uapi -I$(srctree)/tools/include/uapi
 # include ARCH specific config
 -include $(src-perf)/arch/$(SRCARCH)/Makefile