Use pthread mutexes on all Linux platforms.

Bug chromium:710753

Change-Id: Ie74d86de027417579c9c6949aabad1c3ae89ebfc
Reviewed-on: https://swiftshader-review.googlesource.com/9329
Reviewed-by: Corentin Wallez <cwallez@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>

src/Common/MutexLock.hpp

diff --git a/src/Common/MutexLock.hpp b/src/Common/MutexLock.hpp
index d9f4034..65b4d7e 100644
--- a/src/Common/MutexLock.hpp
+++ b/src/Common/MutexLock.hpp
@@ -17,8 +17,8 @@
 
 #include "Thread.hpp"
 
-#ifdef __ANDROID__
-// Use an actual mutex on Android. Since many processes may use SwiftShader
+#if defined(__linux__)
+// Use a pthread mutex on Linux. Since many processes may use SwiftShader
 // at the same time it's best to just have the scheduler overhead.
 #include <pthread.h>