cmake: Clarify error if -P script does not exist
Before this MR, in cmake -P
script mode, the error given if the path is not a file is not clear:
cmake -P .
CMake Error: Error processing file: .
This simple change lets the user know that the specified script path is not a file. This is useful often for small typos like lower case "eye" vs lower case "ell" and similar.
cmake -P .
CMake Error: Not a file: .
Edited by scivision