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

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