Win32: Fix a minor fullscreen bug.
If the window is maximized before going fullscreen, the taskbar appears on top, which is not desirable.
Also, apply the maximized state properly again after exiting, if the user had the window maximized.
One last buildfix (please correct if GL_FUNC_ADD is wrong, I just wanted buildbot to work again). https://github.com/hrydgard/ppsspp/pull/6679 should replace this soon.
Qt: Allow building with system ffmpeg. Also update b.sh to set cmake and qmake flags in case --qt is at the end of the arguments.
Merge pull request #6651 from thedax/win32-fullscreen

Win32: Fix a minor fullscreen bug.
Qt: Change target name to ppsspp by default.Install icons and desktop file on Linux. Use a different builddir than SDL by default.
Should help distros packaging ppsspp. Note: if you currently use PPSSPPQt, you will need to move the config dir from PPSSPPQt to ppsspp.
For distro packagers, you can now use PREFIX and DESTDIR for installs.
Note the location of a memset variant.
Premultiply for doubled alpha blending if possible.

This makes the effect more accurate where the values were being clamped
before.  Some obscure methods of blending may be slower.
Avoid recalculating replaceBlend so many times.
Avoid premultiplying easy fixed colors.
Dirty the fixed color when premultiplying.
Avoid using fbo copies for the common 2a + 1-2a.

We won't even get it right that often since the copy doesn't deal with
overlap properly.
Improve a possible obscure blend mode.

Seems like this would be likely to get overlap problems.
Optimize fixed color blending that isn't blending.

Gods Eater Burst uses this, for example.
More correctly blend when hitting the frame cap.

If we hit too many blits per frame, fall back correctly in the shader.
Add a hack for Silent Hill games.

Either way has different problems, but it sounds like this will work
better for Silent Hill.  Probably still rendering wrong, unfortunately.