While Cmake automatically adjusts the cc calls for building the main compiler, the cc calls we generate through saccc have to be adjusted to the needs of the latest incarnation of Apple Clang.
The main problem is that when cc is called with the full path, -isysroot needs to be provided to allow the compiler to find the standard includes such as <memory.h>. Without that flag, the compiler looks in /usr/include, which, as of lately, no longer exist on MacOS systems.