Sync with upstream @24213649.

Adding GNU/kFreeBSD support. As requested here:
http://code.google.com/p/leveldb/issues/detail?id=38

Use uint64_t instead of size_t in MemEnvTest. As pointed out at
http://code.google.com/p/leveldb/issues/detail?id=41

build_detect_platform

@@ -35,6 +35,11 @@ case `uname -s` in
         echo "PLATFORM_CFLAGS=-D_REENTRANT -DOS_FREEBSD"  >> build_config.mk
         echo "PLATFORM_LDFLAGS=-lpthread" >> build_config.mk
         ;;
+    GNU/kFreeBSD)
+        PLATFORM=OS_FREEBSD
+        echo "PLATFORM_CFLAGS=-pthread -DOS_FREEBSD"  >> build_config.mk
+        echo "PLATFORM_LDFLAGS=-lpthread -lrt" >> build_config.mk
+        ;;
     *)
         echo "Unknown platform!"
         exit 1

helpers/memenv/memenv_test.cc

@@ -26,7 +26,7 @@ class MemEnvTest {
 };
 
 TEST(MemEnvTest, Basics) {
-  size_t file_size;
+  uint64_t file_size;
   WritableFile* writable_file;
   std::vector<std::string> children;