1/15 wsprintfA: cap output and width, consume unhandled args

[avanturist888]

Three bugs in wsprintfA, which came in with my earlier commit, so these are mine to fix:

• No output cap. The real one writes at most 1024 characters including the nul, and callers size their buffers for that; this wrote however much the format produced, so a long %s runs past the caller's buffer into whatever follows it.
• The field width is parsed unbounded into a usize that then sizes an allocation here, so %2000000000d asks for 2GB of padding, and width * 10 overflows on a long enough digit run.
• An unhandled specifier printed %f but did not consume its argument, so every argument after it read the wrong stack slot. wsprintfA(buf, "%f fps in %s", flt, name) makes %s treat the float's low dword as a pointer.

First of the small PRs replacing #1, per the discussion there.