Initial merge of Emscripten port!

With this commit, you can compile SDL2 with Emscripten
( http://emscripten.org/ ), and make your SDL-based C/C++ program
into a web app.

This port was due to the efforts of several people, including: Charlie Birks,
Sathyanarayanan Gunasekaran, Jukka Jylänki, Alon Zakai, Edward Rudd,
Bruce Mitchener, and Martin Gerhardy. (Thanks, everyone!)

--HG--
extra : rebase_source : 97af74c8a5121e926ebe89f123536b5dd6681695

src/filesystem/emscripten/SDL_sysfilesystem.c

@@ -0,0 +1,68 @@
+/*
+  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"
+
+#ifdef SDL_FILESYSTEM_EMSCRIPTEN
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+/* System dependent filesystem routines                                */
+#include <errno.h>
+#include <sys/stat.h>
+
+#include "SDL_error.h"
+#include "SDL_filesystem.h"
+
+#include <emscripten/emscripten.h>
+
+char *
+SDL_GetBasePath(void)
+{
+    char *retval = "/";
+    return SDL_strdup(retval);
+}
+
+char *
+SDL_GetPrefPath(const char *org, const char *app)
+{
+    const char *append = "/libsdl/";
+    char *retval;
+    size_t len = 0;
+
+    len = SDL_strlen(append) + SDL_strlen(org) + SDL_strlen(app) + 3;
+    retval = (char *) SDL_malloc(len);
+    if (!retval) {
+        SDL_OutOfMemory();
+        return NULL;
+    }
+
+    SDL_snprintf(retval, len, "%s%s/%s/", append, org, app);
+
+    if (mkdir(retval, 0700) != 0 && errno != EEXIST) {
+        SDL_SetError("Couldn't create directory '%s': '%s'", retval, strerror(errno));
+        return NULL;
+    }
+
+    return retval;
+}
+
+#endif /* SDL_FILESYSTEM_EMSCRIPTEN */
+
+/* vi: set ts=4 sw=4 expandtab: */