Support dedicated path for skipping varints

PiperOrigin-RevId: 931345587

upb/wire/reader.h

diff --git a/upb/wire/reader.h b/upb/wire/reader.h
index d190022..0a82bd7 100644
--- a/upb/wire/reader.h
+++ b/upb/wire/reader.h
@@ -56,8 +56,14 @@
 // by calling upb_EpsCopyInputStream_IsDone().
 UPB_INLINE const char* upb_WireReader_SkipVarint(
     const char* ptr, upb_EpsCopyInputStream* stream) {
-  uint64_t val;
-  return upb_WireReader_ReadVarint(ptr, &val, stream);
+  UPB_PRIVATE(upb_EpsCopyInputStream_ConsumeBytes)(stream, 10);
+  const char* bound = ptr + 10;
+  do {
+    if ((*(ptr++) & 0x80) == 0) {
+      return ptr;
+    }
+  } while (ptr != bound);
+  return UPB_PRIVATE(upb_EpsCopyInputStream_ReturnError)(stream);
 }
 
 // Reads a varint indicating the size of a delimited field into `size`, or