Variables may be used uninitialized

[strk]

There are 3 possible uninitialized variable uses warned about by GCC (-Wall):

pc_filter.c:218:11: warning: ‘paout’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  PCPATCH *paout;
           ^
pc_patch_ght.c:557:8: warning: ‘err’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     if ( err != GHT_OK || ! tree_filtered )
        ^
pc_schema.c:544:21: warning: ‘s’ may be used uninitialized in this function [-Wmaybe-uninitialized]
      s->compression = compression;
                     ^

See
https://travis-ci.org/pgpointcloud/pointcloud/builds/49436929