Add object files to default ignore patterns

[malept]

Have you read the section in CONTRIBUTING.md about pull requests?

Yes

Summarize your changes:

Avoids the step of having to ignore .o files when signing the app for OSX/macOS (per the Electron docs). Also ignore Windows .obj files for completeness.

@jlord @kevinsawicki @zeke do you see any potential issues with adding this regex to the default ignore list?

Are your changes appropriately documented?

Yes

Do your changes have sufficient test coverage?

Yes

Does the testsuite pass successfully on your local machine?

Yes

[kevinsawicki]

do you see any potential issues with adding this regex to the default ignore list?

Looks good to me 👍

Somewhat related, here are the native module build folder ignore patterns Atom uses:

https://github.com/atom/atom/blob/c45b978816c111837753dbc4fe9f762e522a2c24/script/lib/include-path-in-packaged-app.js#L43-L49

[zeke]

Looks like I'm late to the party, but why does this new regex start with a backslash? All the others start with a slash...

'\\.o(bj)?$'

[malept]

The others start with a slash because they indicate a folder name. This indicates a file extension.

[zeke]

got it. thanks.