minnnasm.nasm creates read-only files

[aakoskin]

When built and ran, minnnasm.nasm creates read-only files under MS-DOS 5.0:

A:>minnnasm.com -f bin minnnasm.asm -o foo.com

A:>del foo.com Access denied

This also makes two-pass compilations fail:

A:>foo.com -O9 -f bin minnnasm.asm -o bar.com error: couldn't open 'bar.com' as output file

The bug seems to be in creat_ routine of the NASM version - a wrong bit is checked (should be al,0x80 instead of ah,1). The C version (mininasm.c) works fine.