[sql] Import reference version of SQLite 3.8.7.4.

third_party/sqlite/sqlite-src-3080704/src/mutex.h

 /*
 ** 2007 August 28
 **
 ** The author disclaims copyright to this source code.  In place of
 ** a legal notice, here is a blessing:
 **
 **    May you do good and not evil.
 **    May you find forgiveness for yourself and forgive others.
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
 **
 ** This file contains the common header for all mutex implementations.
 ** The sqliteInt.h header #includes this file so that it is available
 ** to all source files.  We break it out in an effort to keep the code
 ** better organized.
 **
 ** NOTE:  source files should *not* #include this header file directly.
 ** Source files should #include the sqliteInt.h file and let that file
 ** include this one indirectly.
 */
 
 
 /*
 ** Figure out what version of the code to use.  The choices are
 **
 **   SQLITE_MUTEX_OMIT         No mutex logic.  Not even stubs.  The
-**                             mutexes implemention cannot be overridden
+**                             mutexes implementation cannot be overridden
 **                             at start-time.
 **
 **   SQLITE_MUTEX_NOOP         For single-threaded applications.  No
 **                             mutual exclusion is provided.  But this
 **                             implementation can be overridden at
 **                             start-time.
 **
 **   SQLITE_MUTEX_PTHREADS     For multi-threaded applications on Unix.
 **
 **   SQLITE_MUTEX_W32          For multi-threaded applications on Win32.
-**
-**   SQLITE_MUTEX_OS2          For multi-threaded applications on OS/2.
 */
 #if !SQLITE_THREADSAFE
 # define SQLITE_MUTEX_OMIT
 #endif
 #if SQLITE_THREADSAFE && !defined(SQLITE_MUTEX_NOOP)
 #  if SQLITE_OS_UNIX
 #    define SQLITE_MUTEX_PTHREADS
 #  elif SQLITE_OS_WIN
 #    define SQLITE_MUTEX_W32
-#  elif SQLITE_OS_OS2
-#    define SQLITE_MUTEX_OS2
 #  else
 #    define SQLITE_MUTEX_NOOP
 #  endif
 #endif
 
 #ifdef SQLITE_MUTEX_OMIT
 /*
 ** If this is a no-op implementation, implement everything as macros.
 */
 #define sqlite3_mutex_alloc(X)    ((sqlite3_mutex*)8)
 #define sqlite3_mutex_free(X)
-#define sqlite3_mutex_enter(X)
+#define sqlite3_mutex_enter(X)    
 #define sqlite3_mutex_try(X)      SQLITE_OK
-#define sqlite3_mutex_leave(X)
+#define sqlite3_mutex_leave(X)    
 #define sqlite3_mutex_held(X)     ((void)(X),1)
 #define sqlite3_mutex_notheld(X)  ((void)(X),1)
 #define sqlite3MutexAlloc(X)      ((sqlite3_mutex*)8)
 #define sqlite3MutexInit()        SQLITE_OK
 #define sqlite3MutexEnd()
+#define MUTEX_LOGIC(X)
+#else
+#define MUTEX_LOGIC(X)            X
 #endif /* defined(SQLITE_MUTEX_OMIT) */