[NFC][sanitizer] Remove unused typedef

Author: vitalybuka

compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h

@@ -67,8 +67,6 @@ struct StackTrace {
   static uptr GetCurrentPc();
   static inline uptr GetPreviousInstructionPc(uptr pc);
   static uptr GetNextInstructionPc(uptr pc);
-  typedef bool (*SymbolizeCallback)(const void *pc, char *out_buffer,
-                                    int out_size);
 };
 
 // Performance-critical, must be in the header.