perf tools: Add missing sigqueue() prototype for systems lacking it

There are systems such as the Android NDK API level 24 has the
sigqueue() function but doesn't provide a prototype, adding noise to the
build:

util/evlist.c: In function 'perf_evlist__prepare_workload':
util/evlist.c:1494:4: warning: implicit declaration of function 'sigqueue' [-Wimplicit-function-declaration]
if (sigqueue(getppid(), SIGUSR1, val))
^
util/evlist.c:1494:4: warning: nested extern declaration of 'sigqueue' [-Wnested-externs]

Define a LACKS_SIGQUEUE_PROTOTYPE define so that code needing that can
get a prototype.

Checked in the bionic git repo to be available since level 23:

https://android.googlesource.com/platform/bionic/+/master/libc/include/signal.h#123

int sigqueue(pid_t __pid, int __signal, const union sigval __value) __INTRODUCED_IN(23);

Cc: Adrian Hunter <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Link: https://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Makefile.config

···
   $(call feature_check,bionic)
   ifeq ($(feature-bionic), 1)
     BIONIC := 1
+    CFLAGS += -DLACKS_SIGQUEUE_PROTOTYPE
     EXTLIBS := $(filter-out -lrt,$(EXTLIBS))
     EXTLIBS := $(filter-out -lpthread,$(EXTLIBS))
   endif

tools/perf/util/evlist.c

···
 #include <linux/log2.h>
 #include <linux/err.h>
 
+#ifdef LACKS_SIGQUEUE_PROTOTYPE
+int sigqueue(pid_t pid, int sig, const union sigval value);
+#endif
+
 #define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
 #define SID(e, x, y) xyarray__entry(e->sample_id, x, y)