bug#34106: 27.0.50; master build failed with MSYS2/MinGW-w64

[Eli Zaretskii]

> From: Andy Moreton <andrewjmoreton@gmail.com>
> Date: Wed, 16 Jan 2019 17:44:10 +0000
> 
> The MSYS2/Mingw-w64 build also has a warning:
> 
> C:/emacs/git/emacs/master/src/emacs.c: In function 'load_pdump':
> C:/emacs/git/emacs/master/src/emacs.c:752:28: warning: field precision 
> specifier '.*' expects argument of type 'int', but argument 3 has type 
> 'size_t' {aka 'long long unsigned int'} [-Wformat=]
>      sprintf (dump_file, "%.*s%s", argv0_len - 4, argv[0], suffix);
>                           ~~^~     ~~~~~~~~~~~~~
> 
> The following patch fixes the warning, and fixes the bug above without
> needing a cast:

Thanks, pushed.