fix unused variables in third-party

hphp/third_party/double-conversion/src/strtod.cc

@@ -506,7 +506,9 @@ float Strtof(Vector<const char> buffer, int exponent) {
   double double_previous = Double(double_guess).PreviousDouble();
 
   float f1 = static_cast<float>(double_previous);
+#ifdef DEBUG
   float f2 = float_guess;
+#endif
   float f3 = static_cast<float>(double_next);
   float f4;
   if (is_correct) {

hphp/third_party/folly/folly/experimental/symbolizer/Dwarf.cpp

@@ -639,7 +639,6 @@ bool Dwarf::LineNumberVM::nextDefineFile(folly::StringPiece& program,
     auto length = readULEB(program);
     // the opcode itself should be included in the length, so length >= 1
     enforce(length != 0, "invalid extended opcode length");
-    auto extendedOpcode = read<uint8_t>(program);
     --length;
 
     if (opcode == DW_LNE_define_file) {