--with-prrte=internal is ignored if a valid external prrte is available

[abouteiller]

configure option --with-prrte=internal is ignored when an external, valid PRRTE version is found in PATH etc.

Background information

What version of Open MPI are you using? (e.g., v4.1.6, v5.0.1, git branch name and hash, etc.)

Visible in main and v5.x

Fix

This is a simple error in config/ompi_setup_prrte.m4, fix incoming