If a non-console Windows SDL program has a non-quoted 0th argument followed
optionally by more non-quoted arguments and then by an empty quoted argument,
it will crash (attempts to dereference a NULL pointer).

In other words, something like this:
test.exe [non-quoted args] "" [...]

The fix is a one-liner in ParseCommandLine() of
src/main/win32/SDL_win32_main.c.

You can test this with any non-console SDL program on windows like this:
1) Open a console (cmd.exe)
2) Launch the program in one of the following ways:
program ""
program arg1 ""
program arg1 "" arg3

These will not cause a crash:
"program" [...]
program "arg1" ""

When a Windows program is launched from Explorer, its 0th argument seems to
always be quoted, so it won't be a problem in that case.

I've tested this on Windows XP SP3 and Windows 7.