coffimplib silently overwrites a library with a mixed-case extension

[dlang-bugzilla-migration]

Transferred from: https://issues.dlang.org/show_bug.cgi?id=2620

User snake.scaly reported (2009-Jan-26 18:00:00):

coffimplib, when run with only one library as an argument, usually complains about not being able to overwrite the library. Nevertheless it will silently overwrite the library if its extension isn't all-lowercase. This happens quite often to me because most of libraries in Microsoft Platform SDK are capitalized this way.

$ coffimplib bufferoverflowu.lib
output file 'bufferoverflowu.lib' would overwrite input file, use -f to force it
$ coffimplib Certadm.lib
output file 'Certadm.lib' would overwrite input file, use -f to force it
$ coffimplib ComDlg32.Lib
(nothing)

CC @WalterBright : You're the only one that can handle such bugs as they are on DigitalMars tools.