[MacPorts] #43204: Change BZIP2 variable name for configure script

[MacPorts]

#43204: Change BZIP2 variable name for configure script
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  Reporter:  eborisch@…  |      Owner:  macports-tickets@…
      Type:  defect      |     Status:  closed
  Priority:  Normal      |  Milestone:
 Component:  base        |    Version:  2.2.1
Resolution:  fixed       |   Keywords:
      Port:              |
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Comment (by jeremyhu@…):

 > Note that anyone performing TOOL=PATH ./configure will still get
 (essentially) the previous behavior -- so this shouldn't break anyone's
 custom build that was relying on setting the tool paths in environment
 variables. This occurs because $with_tool will be unset, and
 AC_PATH_PROG(TOOL, ...) will be overridden if the variable TOOL is set.
 (They may not now be marked as precious, but that's another level of
 autoconf grokking that I'm not at...)

 Oh, so THIS is why my build script hasn't been working right for months...

 This actually doesn't do the same thing for people setting environment
 variables with AC_ARG_VAR.  AC_ARG_VAR results in the value being cached
 whereas this does not.

 For example, I check ac_cv_env_BZIP2_value and others to see what base was
 built with when determining if I need to rebuild base.  This new approach
 never saves those in the autoconf cache, so I end up rebuilding base every
 time I do an update.

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Ticket URL: <https://trac.macports.org/ticket/43204#comment:14>
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