[MacPorts] #55583: port:snappy : restore shared library build (and use the up-to-date cmake PG)

[MacPorts]

#55583: port:snappy : restore shared library build (and use the up-to-date cmake
PG)
--------------------+--------------------
 Reporter:  RJVB    |      Owner:
     Type:  defect  |     Status:  new
 Priority:  Normal  |  Milestone:
Component:  ports   |    Version:
 Keywords:          |       Port:  snappy
--------------------+--------------------
 The recent upgrade of port:snappy had to migrate to CMake but did so using
 the obsolete cmake 1.0 PG, doesn't follow the out-of-source build dir
 guideline, and above all lost the shared library which isn't built by
 default.

 The attached patch updates the cmake PG to 1.1 (which does out-of-source
 builds by default), and activates the shared library build.

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Ticket URL: <https://trac.macports.org/ticket/55583>
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