Fix grcc compilation with python3 by adding local subdirs to __path__

As the directory structure in the repository is different then the one
after the package gets installed we need to add those subdirectories to
the __path__ otherwise python3 is not able to load the modules using the
relative import syntax and grcc compilation and some unit tests fail.

Mofiy __path__ only when the CMAKE_BINARY_DIR environment variable is
present.

Revert "grgsm_livemon: Set cell_allocation to [0]"

This reverts commit 013d4c258c6ad31c2581f0caa4eee3aa609fd9de.

Change-Id: I223fd6181e8e36027039301186b671712a597ff8
diff --git a/apps/grgsm_livemon.grc b/apps/grgsm_livemon.grc
index 941f816..e8bf4a5 100644
--- a/apps/grgsm_livemon.grc
+++ b/apps/grgsm_livemon.grc
@@ -360,7 +360,7 @@
   parameters:
     affinity: ''
     alias: ''
-    cell_allocation: '[0]'
+    cell_allocation: '[arfcn.downlink2arfcn(fc)]'
     comment: ''
     maxoutbuf: '0'
     minoutbuf: '0'