col: add -h option

[mknos]

• GNU and BSD versions of col support -h which is the same as the default operation of col
• In those versions -h and -x given together negate each other, so the final one wins
• getopts() doesn't disclose the order of options, so document that -x takes precedence over -h if both are given
• Sync usage() function
• test1: "perl col < col | md5sum" --> normal output
• test2: "perl col -h < col | md5sum" --> same output as test1
• test3: "perl col -x < col | md5sum" --> multiple spaces output
• test4: "perl col -xh < col | md5sum" --> honour -x despite -h coming last; same output as test3

[coveralls]

Pull Request Test Coverage Report for Build 10862835151

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.7%) to 73.069%

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Totals
Change from base Build 10851028782:	-0.7%
Covered Lines:	350
Relevant Lines:	479

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💛 - Coveralls

[briandfoy]

changes: add -h for compatibility, although that's what we already do