FIX: Fix all symbols sentinel value

Author: threecgreen

example/symbology_resolve.cpp

@@ -8,7 +8,7 @@
 #include "databento/symbology.hpp"
 
 int main(int argc, char* argv[]) {
-  if (argc < 6) {
+  if (argc < 7) {
     std::cerr << "USAGE: symbology-resolve <DATASET> <STYPE_IN> <STYPE_OUT> "
                  "<START_DATE> <END_DATE> <SYMBOLS...>\n";
     return EX_USAGE;

include/databento/symbology.hpp

@@ -8,7 +8,7 @@
 
 namespace databento {
 // Sentinel value for requesting all symbols
-static const std::vector<std::string> kAllSymbols{};
+static const std::vector<std::string> kAllSymbols{"*"};
 
 struct StrMappingInterval {
   // YYYY-MM-DD