updated protobuf to 3.18.1

external/include/google/protobuf/stubs/stl_util.h

@@ -35,6 +35,8 @@
 
 #include <google/protobuf/stubs/common.h>
 
+#include <algorithm>
+
 namespace google {
 namespace protobuf {
 
@@ -48,6 +50,18 @@ inline void STLStringResizeUninitialized(std::string* s, size_t new_size) {
   s->resize(new_size);
 }
 
+// As above, but we make sure to follow amortized growth in which we always
+// increase the capacity by at least a constant factor >1.
+inline void STLStringResizeUninitializedAmortized(std::string* s,
+                                                  size_t new_size) {
+  const size_t cap = s->capacity();
+  if (new_size > cap) {
+    // Make sure to always grow by at least a factor of 2x.
+    s->reserve(std::max(new_size, 2 * cap));
+  }
+  STLStringResizeUninitialized(s, new_size);
+}
+
 // Return a mutable char* pointing to a string's internal buffer,
 // which may not be null-terminated. Writing through this pointer will
 // modify the string.