Add application/x-msdownload and subtypes

application/x-msdownload is what Microsoft Windows uses for EXE and DLL files, so that type is commonly found on the WWW and in other contexts. It is an umbrella type for anything with a .exe or .dll file extension, among others.

application/x-dosexec is what the file utility uses for DOS executables specifically. According to the File Format Problem wiki: "It's not clear if there is any completely reliable way to identify a file as strictly DOS EXE, except in the negative (i.e., it looks like EXE, and is not a valid NE, PE, etc., file)...If the relocation table offset is from 28 to 63...it is pretty certainly DOS EXE."

application/x-ms-ne-executable is what the file utility uses for 16-bit Windows libraries and executables.

application/vnd.microsoft.portable-executable is the IANA standard type for 32-bit and 64-bit Windows libraries and executables, as well as EFI executables.

With these changes, application/x-ms-dos-executable is considered deprecated. For now it is an alias of application/x-msdownload, but in the future it may change to be an alias of application/x-dosexec.

helloworld-*.exe was compiled with Open Watcom from the following C source code:

#include <stdio.h>

int main(void)
{
    puts("Hello World!");
    return 0;
}

https://github.com/file/file/blob/171c73b67ca692550882e0b8ab3c2a1f16ab1e00/magic/Magdir/msdos https://www.iana.org/assignments/media-types/application/vnd.microsoft.portable-executable http://fileformats.archiveteam.org/wiki/MS-DOS_EXE http://fileformats.archiveteam.org/wiki/New_Executable http://fileformats.archiveteam.org/wiki/Portable_Executable