perf tools: Remove needless 'extern' from function prototypes

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-w246stf7ponfamclsai6b9zo@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/symbol.h

@@ -34,8 +34,8 @@
 #endif
 
 #ifdef HAVE_LIBELF_SUPPORT
-extern Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
-				GElf_Shdr *shp, const char *name, size_t *idx);
+Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
+			     GElf_Shdr *shp, const char *name, size_t *idx);
 #endif
 
 #ifndef DMGL_PARAMS