[MacPorts] #73953: giflib5: install under libexec

[MacPorts]

#73953: giflib5: install under libexec
-------------------------+-------------------------
  Reporter:  mohd-akram  |      Owner:  Schamschula
      Type:  defect      |     Status:  assigned
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:
Resolution:              |   Keywords:
      Port:  giflib5     |
-------------------------+-------------------------

Comment (by Schamschula):

 I'm working on doing just that as a part of addressing #73603

 So far I have moved {{{giflib}}} to {{{giflib4}}}, {{{giflib5}}} and
 (temporarily) {{{giflib6}}} all to {{{${prefix}/libexec}}}. {{{giflib6}}}
 will become {{{giflib}}} after testing.

 The current step is to see which ports are compatible with each version.
 That entails modifying the Portfiles to point at the correct include and
 lib directories and then test building against the current version,
 followed by the newer versions.

-- 
Ticket URL: <https://trac.macports.org/ticket/73953#comment:1>
MacPorts <https://www.macports.org/>
Ports system for macOS