TT#65907 Speedup 'ngcpcfg build' on 25% for non-docker installations

We are calling slow Perl command to move files to workaround Docker problem
and losing 25% of performance on every NGCP installation in production.
Let's call slow workaround when it is necessary only (in Docker).

Command: time ngcpcfg build
Original results: real   0m19.976s
Current  results: real   0m15.286s

Change-Id: Iac787c0fcdb4182d71b6305ebbba5ea3193e76c8

helper/build_config

@@ -93,8 +93,12 @@ move()
   local src="$1"
   local dst="$2"
 
-  perl -MFile::Copy=mv \
-       -E "mv('${src}', '${dst}') or die 'error: cannot move $src to $dst: \$!\n'"
+  if [ -e /.dockerinit ] || [ -e /.dockerenv ] ; then
+    perl -MFile::Copy=mv \
+         -E "mv('${src}', '${dst}') or die 'error: cannot move $src to $dst: \$!\n'"
+  else
+    mv "${src}" "${dst}"
+  fi
 
   rm -f "${src}"
 }