Log Message:
Update to exctags to 5.5.4.

Changes since 5.5.0:

* Added support for Perl labels.
* Added support for Perl "use constant" [Perl, Patch #853704, Feature \ 
Request
  #710017].
* Added support for package qualification of tags, removing useless \ 
"package"
  tag kind [Perl, Feature Request #448887].
* Added support for "and" keyword [SML, Bug #816636].
* Added support for variables [PHP].
* Added tags for local variables for C-based languages [C/C++/C#/Java/Vera,
  Feature Request #449503].
* Added support for tags for labels [PL/SQL].
* Added support for tags for constant definitions [PHP].

And many bug fixes.