Revert " Fix infinite loop in split_by_comma_or_colon(). (#1332)"

This reverts commit 0c74e82.

src/cmdline.cc

@@ -422,16 +422,14 @@ static std::vector<std::string_view>
 split_by_comma_or_colon(std::string_view str) {
   std::vector<std::string_view> vec;
 
-  while (!str.empty()) {
+  for (;;) {
     i64 pos = str.find_first_of(",:");
     if (pos == str.npos) {
       vec.push_back(str);
       break;
     }
-    if (pos > 0) {
-      vec.push_back(str.substr(0, pos));
-    }
-    str = str.substr(pos + 1);
+    vec.push_back(str.substr(0, pos));
+    str = str.substr(pos);
   }
   return vec;
 }