perf llvm-add2line: Remove unused symbol_conf.h include

Remove unused symbol_conf.h include.

First, it's just unused. Second, it's problematic since this is a C++
file, and most perf headers don't compile as C++. So if any other
includes are added to symbol_conf.h, it may break the build.

Signed-off-by: Dmitriy Vyukov <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/llvm-c-helpers.cpp

···
 extern "C" {
 #include <linux/zalloc.h>
 }
-#include "symbol_conf.h"
 #include "llvm-c-helpers.h"
 
 extern "C"