[Chapel Merge] Fix readf regexp handling at end of file

Branch: refs/heads/master
Revision: df875ea
Author: mppf
Log Message:

Merge pull request #16902 from mppf/fix-16891

Fix readf regexp handling at end of file

Resolves #16891

  • [x] full local testing

Modified Files:
A test/regexp/ferguson/bug-16891.chpl
A test/regexp/ferguson/bug-16891.good
A test/regexp/ferguson/bug-16891.txt
M modules/standard/IO.chpl
M runtime/src/qio/regexp/re2/re2-interface.cc

Compare: https://github.com/chapel-lang/chapel/compare/d8b55ba35af4...df875eaa88fb