* [openmpi] 5.0.0.rc10 onwards needs munge
This is the error you will see when munge is missing from `PKG_CONFIG_PATH`:
```
configure:63942: checking for pmix pkg-config cflags
configure:63956: check_package_pkgconfig_run_results=Package munge was not found in the pkg-config search path.
Perhaps you should add the directory containing `munge.pc'
to the PKG_CONFIG_PATH environment variable
Package 'munge', required by 'pmix', not found
configure:63959: $? = 1
configure:63966: pkg-config output: Package munge was not found in the pkg-config search path.
Perhaps you should add the directory containing `munge.pc'
to the PKG_CONFIG_PATH environment variable
Package 'munge', required by 'pmix', not found
configure:63972: result: error
configure:63974: error: An error occurred retrieving pmix cppflags from pkg-config
```
* Use same PKG_CONFIG_PATH defaults for ompi+pmix+prrte
The issue I tried to fix in https://github.com/spack/spack/pull/36105 comes from
different default search paths in different `pkg-config` executables used in
`openmpi` and `pmix` package. As these tools (`openmpi`, `pmix`, and `prrte`)
all use the same mechanisms to detect dependencies, the `pkg-config` environment
they use should also be equal.
38383743e7