php: Fix support for PHP 7.2+ trailing comma in grouped use statements

[b4n]

https://www.php.net/manual/en/migration72.new-features.php#migration72.new-features.trailing-comma-in-grouped-namespaces

[coveralls]

Coverage increased (+0.0003%) to 87.052% when pulling 2312126 on b4n:php/php72-use-trailing-comma into 710529f on universal-ctags:master.

[codecov]

Codecov Report

Merging #2742 (2312126) into master (710529f) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2742   +/-   ##
=======================================
  Coverage   86.96%   86.96%           
=======================================
  Files         190      190           
  Lines       40350    40351    +1     
=======================================
+ Hits        35092    35093    +1     
  Misses       5258     5258           

Impacted Files	Coverage Δ
parsers/php.c	98.72% <100.00%> (+<0.01%)	⬆️

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