perf/ui/gtk: Fix gtk2 build

Ravi Bangoria reported an issue when doing the gtk2 feature detection on
Fedora 31, where some types got deprecated:

  /usr/include/gtk-2.0/gtk/gtktypeutils.h:236:1: error: ‘GTypeDebugFlags’ is deprecated [-Werror=deprecated-declarations]
    236 | void            gtk_type_init   (GTypeDebugFlags    debug_flags);

Fix this for perf by allowing the compile to pass with deprecated
symbols via the -Wno-deprecated-declarations compiler directive.
Reported-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jelle van der Waa <jelle@vdwaa.nl>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200113104358.123511-2-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/build/feature/Makefile

@@ -197,7 +197,7 @@ $(OUTPUT)test-libcrypto.bin:
 	$(BUILD) -lcrypto
 
 $(OUTPUT)test-gtk2.bin:
-	$(BUILD) $(shell $(PKG_CONFIG) --libs --cflags gtk+-2.0 2>/dev/null)
+	$(BUILD) $(shell $(PKG_CONFIG) --libs --cflags gtk+-2.0 2>/dev/null) -Wno-deprecated-declarations
 
 $(OUTPUT)test-gtk2-infobar.bin:
 	$(BUILD) $(shell $(PKG_CONFIG) --libs --cflags gtk+-2.0 2>/dev/null)

tools/perf/ui/gtk/Build

-CFLAGS_gtk += -fPIC $(GTK_CFLAGS)
+CFLAGS_gtk += -fPIC $(GTK_CFLAGS) -Wno-deprecated-declarations
 
 gtk-y += browser.o
 gtk-y += hists.o