Update static SkMutex to remove static initializer on Linux.

src/core/SkDeviceProfile.cpp

Index: src/core/SkDeviceProfile.cpp
===================================================================
--- src/core/SkDeviceProfile.cpp	(revision 10125)
+++ src/core/SkDeviceProfile.cpp	(working copy)
@@ -7,6 +7,7 @@
 
 
 #include "SkDeviceProfile.h"
+#include "SkThread.h"
 
 SK_DEFINE_INST_COUNT(SkDeviceProfile)
 
@@ -45,7 +46,7 @@
     return SkNEW_ARGS(SkDeviceProfile, (gammaExp, contrast, config, level));
 }
 
-static SkMutex gMutex;
+SK_DECLARE_STATIC_MUTEX(gMutex);
 static SkDeviceProfile* gDefaultProfile;
 static SkDeviceProfile* gGlobalProfile;