fix some issues with Linux compatibility,

see Issue 409

src/BulletMultiThreaded/MiniCL.cpp

@@ -27,7 +27,7 @@ subject to the following restrictions:
 #include "LinearMath/btMinMax.h"
 #include <stdio.h>
 
-#define DEBUG_MINICL_KERNELS 1
+//#define DEBUG_MINICL_KERNELS 1
 
 static char* spPlatformID = "MiniCL, SCEA";
 

src/BulletMultiThreaded/PosixThreadSupport.h

@@ -18,7 +18,9 @@ subject to the following restrictions:
 #include "PlatformDefinitions.h"
 
 #ifdef USE_PTHREADS  //platform specific defines are defined in PlatformDefinitions.h
+#ifndef _XOPEN_SOURCE
 #define _XOPEN_SOURCE 600 //for definition of pthread_barrier_t, see http://pages.cs.wisc.edu/~travitch/pthreads_primer.html
+#endif //_XOPEN_SOURCE
 #include <pthread.h>
 #include <semaphore.h>