style: Various fixes suggested by Clang

[mgrabovsky]

• Use *_MAX constants instead of -1 in unsigned comparisons.
• Use fitting types (size_t, unsigned long, etc.) where appropriate instead of the generic int.
• Correct parenthesization for bitfield tests.
• Document when a core stack frame's address may be unknown.

[mkutlak]

Please split the commit to multiple ones. Each commit should cover one topic:

• Use *_MAX constants instead of -1 in unsigned comparisons.
• Use fitting types (size_t, unsigned long, etc.) where appropriate instead of the generic int.
• Correct parenthesization for bitfield tests.
• Document when a core stack frame's address may be unknown.

[mgrabovsky]

Commit split.

[ernestask]

Also, https://github.com/abrt/satyr/pull/288/commits/abb74839ea2c091a33e88192c123088615208585 could be squashed with https://github.com/abrt/satyr/pull/288/commits/5b278d4b45142f667fdbd185587d4c5b2748bf51, since you’re doing the same, essentially.

[ernestask]

Otherwise LGTM.

[mgrabovsky]

OK, should be fine now.