On z/OS, the following error message is not matched correctly in lit tests.
```
EDC5129I No such file or directory.
```
This patch uses a lit config substitution to check for platform specific error messages.
Reviewed By: muiez, jhenderson
Differential Revision: https://reviews.llvm.org/D95246
To improve consistency and avoid unneeded shell feature (output
redirection).
While here, make other changes to improve consistency
--docnum 1 => --docnum=1
-docnum=x => --docnum=x
Error message outputs with lowercase on Windows.
Made test work on Widnows.
For example:
llvm-lipo: error: 'i386': no such file or directory
llvm-svn: 367266
Replaces specified architecture in universal binary input file with
slice from the file_name argument passed into the replace command.
Differential Revision: https://reviews.llvm.org/D65247
llvm-svn: 367248