cmMakefile: Refactor AddCMakeDependFile  and AddCMakeOutputFile.

AddCMakeDependFile and AddCMakeOutputFile both store as std::string
and all calling sites use std::string. So instead of creating more
temporary objects, lets just use std::strings.
Merge topic 'makefile_AddCMakeOutputFile_signature'

6dbd4a5 cmMakefile: Refactor AddCMakeDependFile  and AddCMakeOutputFile.