diff_order_for_section_name warning instead of crash

[HaydnTrigg]

Commit f2f813e added in a function diff_order_for_section_name which crashes out with the error message Failed to find right side symbol for paired left side symbol

This change makes this function log a warning instead of crashing out and also provides context for the expected symbol name and section that is expected.

v3.8.1:

v3.7.1:

Patched:

[LagoLunatic]

Is there any scenario where a left symbol will be paired to a right symbol but that right symbol will not be paired to a left symbol? That doesn't sound correct to me and I believe it would cause a number of subtle issues in other parts of objdiff which assume that symbols are paired both ways, which is why I intentionally made it crash here instead of ignoring the bug and incorrectly showing no diff.

A crash is more likely to be reported as a bug than a warning. Actually, where does objdiff even log to, anyway? I've only seen its warnings in the console when running it in debug mode, which most users won't see at all and won't be able to report.