fix wrong module path in tools/create-ccan-tree

[PengZheng]

$ ./create-ccan-tree -b automake  ~/Desktop/third_party array_size
Building ccan_depends, modfiles
Cleaning source tree
Adding ccan/array_size
modfiles: Getting canonical version of directory ccan/array_size: **No such file or directory**
Adding ccan/build_assert
modfiles: Getting canonical version of directory ccan/build_assert: **No such file or directory**
Adding licenses
Adding build infrastructure
Done. ccan source tree built in /home/peng/Desktop/third_party