[mac crash handler] change sprintf -> snprintf to prevent buffer overrun

[sandboxcoder]

Description

Small code improvement to make sure we prevent memory buffer overrun

Motivation and Context

Resolves xcode warning in util-crashhandler. Guards crash handler against buffer overrun

How Has This Been Tested?

Verified this code change by testing function in isolation

Types of changes

• Tweak (non-breaking change to improve existing functionality)

Checklist:

• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.