CYCLONEDDS_HOME using relative path fails

[erwincoumans]

In case someone else runs into this:
When using

export CYCLONEDDS_HOME=~/cyclone_dds

installation failed. Changing into absolute path fixed it.

Tracking down by printing dir in good_directory exposes the issue:

     dir = directory.resolve()
+    print("dir=",dir)
     if not dir.exists():
         return

showing

dir= /media/erwin/ubuntu_extra/dev/roger/cyclonedds-python/~/cyclonedds/install