Revert "perf symbols: Fix mismatched declarations for elf_getphdrnum"

This reverts commit f785f2357673d520a0b7b468973cdd197f336494.

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 <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Frederic Weisbecker <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: "Naveen N. Rao" <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Srikar Dronamraju <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Cc: Victor Kamensky <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/symbol-elf.c

···
 #endif
 
 #ifndef HAVE_ELF_GETPHDRNUM_SUPPORT
-int elf_getphdrnum(Elf *elf, size_t *dst)
+static int elf_getphdrnum(Elf *elf, size_t *dst)
 {
 	GElf_Ehdr gehdr;
 	GElf_Ehdr *ehdr;