Make api.cc malloc consistent with paddle_api.h for PaddleBuf (#22255)

paddle/fluid/inference/api/api.cc

@@ -85,7 +85,7 @@ void PaddleBuf::Resize(size_t length) {
   if (length_ >= length) return;
   if (memory_owned_) {
     Free();
-    data_ = malloc(length);
+    data_ = new char[length];
     length_ = length;
     memory_owned_ = true;
   } else {
@@ -103,7 +103,7 @@ void PaddleBuf::Reset(void *data, size_t length) {
 void PaddleBuf::Free() {
   if (memory_owned_ && data_) {
     PADDLE_ENFORCE_GT(length_, 0UL);
-    free(static_cast<char *>(data_));
+    delete[] static_cast<char *>(data_);
     data_ = nullptr;
     length_ = 0;
   }