Fixes audio for Native Client, and other fixes...

- SDL_NaClMount, SDL_NaClUmount
- Default mounting of https at / in SDL's main function
- More documentation in README-nacl.txt

include/SDL_config.h.in

@@ -336,6 +336,7 @@
 #undef SDL_FILESYSTEM_DUMMY
 #undef SDL_FILESYSTEM_UNIX
 #undef SDL_FILESYSTEM_WINDOWS
+#undef SDL_FILESYSTEM_NACL
 
 /* Enable assembly routines */
 #undef SDL_ASSEMBLY_ROUTINES

include/SDL_system.h

@@ -179,6 +179,22 @@ extern DECLSPEC const char * SDLCALL SDL_WinRTGetFSPathUTF8(SDL_WinRT_Path pathT
 
 #endif /* __WINRT__ */
 
+#ifdef __NACL__
+
+/**
+ *  \name Mount/umount functions
+ *
+ *  Required for RWOps on Native Client
+ */
+/* @{ */
+extern DECLSPEC int SDLCALL SDL_NaClMount(const char* source, const char* target, 
+                                        const char* filesystemtype, 
+                                        unsigned long mountflags, const void *data);
+
+extern DECLSPEC int SDLCALL SDL_NaClUmount(const char *target);
+
+#endif /* __NACL__ */
+
 
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus