Avoid naming conflict of EntryType

Summary:
Fix build break on travis build:

$ OPT=-DTRAVIS V=1 make unity && make clean && OPT=-DTRAVIS V=1 make db_test && ./db_test

......

In file included from unity.cc:65:0:
./table/plain_table_key_coding.cc: In member function ‘rocksdb::Status rocksdb::PlainTableKeyDecoder::NextPrefixEncodingKey(const char*, const char*, rocksdb::ParsedInternalKey*, rocksdb::Slice*, size_t*, bool*)’:
./table/plain_table_key_coding.cc:224:3: error: reference to ‘EntryType’ is ambiguous
   EntryType entry_type;
   ^
In file included from ./db/table_properties_collector.h:9:0,
                 from ./db/builder.h:11,
                 from ./db/builder.cc:10,
                 from unity.cc:1:
./include/rocksdb/table_properties.h:81:6: note: candidates are: enum rocksdb::EntryType
 enum EntryType {
      ^
In file included from unity.cc:65:0:
./table/plain_table_key_coding.cc:16:6: note:                 enum rocksdb::{anonymous}::EntryType
 enum EntryType : unsigned char {
      ^
./table/plain_table_key_coding.cc:231:51: error: ‘entry_type’ was not declared in this scope
     const char* pos = DecodeSize(key_ptr, limit, &entry_type, &size);
                                                   ^
make: *** [unity.o] Error 1

Test Plan:
OPT=-DTRAVIS V=1 make unity

And make sure it doesn't break anymore.

Reviewers: yhchiang, kradhakrishnan, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D36549

table/plain_table_key_coding.cc

@@ -13,7 +13,7 @@ namespace rocksdb {
 
 namespace {
 
-enum EntryType : unsigned char {
+enum PlainTableEntryType : unsigned char {
   kFullKey = 0,
   kPrefixFromPreviousKey = 1,
   kKeySuffix = 2,
@@ -27,7 +27,8 @@ enum EntryType : unsigned char {
 const unsigned char kSizeInlineLimit = 0x3F;
 
 // Return 0 for error
-size_t EncodeSize(EntryType type, uint32_t key_size, char* out_buffer) {
+size_t EncodeSize(PlainTableEntryType type, uint32_t key_size,
+                  char* out_buffer) {
   out_buffer[0] = type << 6;
 
   if (key_size < static_cast<uint32_t>(kSizeInlineLimit)) {
@@ -43,9 +44,9 @@ size_t EncodeSize(EntryType type, uint32_t key_size, char* out_buffer) {
 
 // Return position after the size byte(s). nullptr means error
 const char* DecodeSize(const char* offset, const char* limit,
-                       EntryType* entry_type, uint32_t* key_size) {
+                       PlainTableEntryType* entry_type, uint32_t* key_size) {
   assert(offset < limit);
-  *entry_type = static_cast<EntryType>(
+  *entry_type = static_cast<PlainTableEntryType>(
       (static_cast<unsigned char>(offset[0]) & ~kSizeInlineLimit) >> 6);
   char inline_key_size = offset[0] & kSizeInlineLimit;
   if (inline_key_size < kSizeInlineLimit) {
@@ -221,7 +222,7 @@ Status PlainTableKeyDecoder::NextPrefixEncodingKey(
     const char* start, const char* limit, ParsedInternalKey* parsed_key,
     Slice* internal_key, size_t* bytes_read, bool* seekable) {
   const char* key_ptr = start;
-  EntryType entry_type;
+  PlainTableEntryType entry_type;
 
   bool expect_suffix = false;
   do {