Rely on pthread to implement reader-writer lock for Android

Now that we support API Level 14 (Ice Cream Sandwich) and later only, we can safely assume that pthread is available.

This is just a performance optimization.  No user-visible change is intended.

BUG=none
TEST=none

git-svn-id: https://mozc.googlecode.com/svn/trunk@531 a6090854-d499-a067-5803-1114d4e51264

src/base/mutex.cc

@@ -43,12 +43,6 @@
 
 #if defined(OS_WIN)
 // We do not use pthread on Windows
-#elif defined(OS_ANDROID)
-// pthread rwlock is supported since API Level 9.
-// Currently minimum API Level is 7 so we cannot use it.
-// Note that we cannot use __ANDROID_API__ macro in above condition
-// because it is equal to target API Level, which is greater than
-// min sdk level. Causes runtime crash.
 #elif defined(__native_client__)
 // TODO(team): Consider to use glibc rwlock.
 #else

src/mozc_version_template.txt

@@ -1,6 +1,6 @@
 MAJOR=2
 MINOR=16
-BUILD=2047
+BUILD=2048
 REVISION=102
 # NACL_DICTIONARY_VERSION is the target version of the system dictionary to be
 # downloaded by NaCl Mozc.