Improve errors in sceMpegRingbufferConstruct().

And also make Destruct() not actually null out the ringbuffer, per tests.
Fix mpeg struct header.
Correct errors in sceMpegRingbufferAvailableSize().
Fix warning in MIPS/MIPSAnalyst.cpp
Merge pull request #5029 from pal1000/work

Fix warning in MIPS/MIPSAnalyst.cpp
Merge pull request #5027 from unknownbrackets/mpeg-minor

Correct some basic mpeg functionality to match tests
Added ShortcutActivity class to respond to homescreen shortcut intent.
It will show file dialog and return path to selected file as intent response.
Added simple file chooser dialog,
This is to select game iso when creating homescreen shortcut.

Probably not an ideal solution, could use ppsspp internal GameBrowser later.
Added name to display when user long-press homescreen and choose "Shortcuts".
In our case it's "PPSSPP game".
Added ShortcutActivity class on ppsspp manifest, so it will appears on homescreen shortcuts choice ("PPSSPP game" in our case).
- Moved SHORTCUT_EXTRA_KEY and shortcut query here.

- Call super.setShortcutParam(getIntent().getStringExtra(SHORTCUT_EXTRA_KEY))
before super.onCreate()
- Change SHORTCUT_EXTRA_KEY reference from NativeActivity to PpssppActivity.
Update native
Merge pull request #5023 from valef/android-shortcut

Android homescreen shortcut
Enable depth buffer copies on GLES3 devices without breaking any desktop
Symbian buildfix
Prevent the accelerometer from being mapped to controls directly until we can create sane UI for that.
Also disable some weird axis events we get on Ouya from mapping.
Merge remote-tracking branch 'upstream/master' into fps2

Conflicts:
	native