Avoid aliasing CodedInputStream::buffer_ when parsing little endian integers.

This eliminates an unnecessary reload of buffer_ that occurs (before
this change) after the store to *value.

src/google/protobuf/io/coded_stream.h

@@ -996,8 +996,7 @@ inline const uint8* CodedInputStream::ReadLittleEndian64FromArray(
 inline bool CodedInputStream::ReadLittleEndian32(uint32* value) {
 #if defined(PROTOBUF_LITTLE_ENDIAN)
   if (GOOGLE_PREDICT_TRUE(BufferSize() >= static_cast<int>(sizeof(*value)))) {
-    memcpy(value, buffer_, sizeof(*value));
-    Advance(sizeof(*value));
+    buffer_ = ReadLittleEndian32FromArray(buffer_, value);
     return true;
   } else {
     return ReadLittleEndian32Fallback(value);
@@ -1010,8 +1009,7 @@ inline bool CodedInputStream::ReadLittleEndian32(uint32* value) {
 inline bool CodedInputStream::ReadLittleEndian64(uint64* value) {
 #if defined(PROTOBUF_LITTLE_ENDIAN)
   if (GOOGLE_PREDICT_TRUE(BufferSize() >= static_cast<int>(sizeof(*value)))) {
-    memcpy(value, buffer_, sizeof(*value));
-    Advance(sizeof(*value));
+    buffer_ = ReadLittleEndian64FromArray(buffer_, value);
     return true;
   } else {
     return ReadLittleEndian64Fallback(value);