Fix build on a musl libc Linux.

include/bx/thread.h

@@ -149,7 +149,7 @@ namespace bx
 		{
 #if BX_PLATFORM_OSX || BX_PLATFORM_IOS
 			pthread_setname_np(_name);
-#elif BX_PLATFORM_LINUX || BX_PLATFORM_FREEBSD
+#elif (BX_PLATFORM_LINUX && defined(__GLIBC__)) || BX_PLATFORM_FREEBSD
 			pthread_setname_np(m_handle, _name);
 #elif BX_PLATFORM_WINDOWS && BX_COMPILER_MSVC
 #	pragma pack(push, 8)