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

src/filesystem/nacl/SDL_sysfilesytem.c

@@ -0,0 +1,59 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "../../SDL_internal.h"
+#include "SDL_error.h"
+#include "SDL_filesystem.h"
+
+#ifdef SDL_FILESYSTEM_NACL
+
+/* SDL_RWops on NACL are implemented using nacl_io, and require mount points
+ * to be established before actual file operations are performed
+ * 
+ * Ref: https://developers.google.com/native-client/dev/devguide/coding/nacl_io
+ */
+
+int 
+SDL_NaClMount(const char* source, const char* target, const char* filesystemtype, 
+          unsigned long mountflags, const void *data) {
+    return mount(source, target, filesystemtype, mountflags, data);
+}
+
+int 
+SDL_NaClUmount(const char *target) {
+    return umount(target);
+}
+
+
+char *
+SDL_GetBasePath(void)
+{
+    SDL_Unsupported();
+    return NULL;
+}
+
+char *
+SDL_GetPrefPath(const char *org, const char *app)
+{
+    SDL_Unsupported();
+    return NULL;
+}
+
+#endif /* __NACL__ */