updates to compile ET on macOS M1 systems

[Roland Haas]

On M1 (and freshly installed amd64) macOS systems there are a number of changes to consider:

• HomeBrew installs to /opt/homebrew rather than /opt/local
• PAPI needs more patches to be turned into a no-op (since it does not support darwin)

This is provided in a series of pull requests for flesh and ExternalLibraries:

• https://bitbucket.org/cactuscode/cactus/pull-requests/148
• https://github.com/EinsteinToolkit/ExternalLibraries-PAPI/pull/3
• https://github.com/EinsteinToolkit/ExternalLibraries-FFTW3/pull/1
• https://github.com/EinsteinToolkit/ExternalLibraries-OpenCL/pull/1
• https://github.com/EinsteinToolkit/ExternalLibraries-OpenSSL/pull/1
• https://github.com/EinsteinToolkit/ExternalLibraries-zlib/pull/1
• https://github.com/EinsteinToolkit/ExternalLibraries-hwloc/pull/3
• https://github.com/EinsteinToolkit/ExternalLibraries-pthreads/pull/1

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[Roland Haas]

Please review.

[Roland Haas]

Tested on macOS Ventura, HomeBrew and MacPorts.