SAF_PERFORMANCE_LIB is being improperly set to SAF_USE_INTEL_MKL_LP64 on Apple

[mspanc]

Description

Intel oneAPI Toolkit no longer available for macOS (see leomccormack/SPARTA#90).

However, the current construction of the CMake config sets SAF_PERFORMANCE_LIB to SAF_USE_INTEL_MKL_LP64 as default on Apple while building within SPARTA.

Environment

1. OS: macOS 14.1.2/M1
2. Compiler: AppleClang 15.0.0.15000309

Reproducible Steps

Steps to create the smallest reproducible scenario:

1. Clone the SPARTA repository on macOS 14/M1 and follow instructions from README
2. Run cmake -S . -B build

Expected Output

Apple Accelerate should be always used as default on Apple.

Actual Output

Intel MKL is being used as default on Apple.