Revert "perf symbols: Fix mismatched declarations for elf_getphdrnum"

This reverts commit f785f235.

We have a test to check if elf_getphdrnum() is present, so, if it fails,
we'll get:

  [acme@rhel5 linux]$ cat /tmp/build/perf/feature/test-libelf-getphdrnum.make.output
  cc1: warnings being treated as errors
  test-libelf-getphdrnum.c: In function ‘main’:
  test-libelf-getphdrnum.c:7: warning: implicit declaration of function ‘elf_getphdrnum’
  [acme@rhel5 linux]$

And this block will not be compiled:

  #ifndef HAVE_ELF_GETPHDRNUM_SUPPORT
  static int elf_getphdrnum(Elf *elf, size_t *dst)
  ...
  #endif

So, if elf_getphdrnum() is being defined somewhere, there is a problem
with the test that is not detecting that function, go fix it.

Reported-by: Vinson Lee <vlee@twopensource.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Victor Kamensky <victor.kamensky@linaro.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-qn459fal6acvcvm50i8zxx9k@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>