faiss requires OpenMP which Apple Clang does not ship. Skip faiss
on macOS/apple-clang to prevent conan install failures during warm.
Also restore trailing whitespace in Linux gcc profiles to match
original cache key hash (hashFiles change invalidated all platform
caches, exposing the macOS issue).
tools.build:compiler_executables requires bare executable names, not
'ccache clang' with a space. setup.sh already wraps CC/CXX with ccache
for Meson builds. The warm step's meson compile (Fix 3) populates
ccache for YAMS source. Conan dep ccache will be addressed separately.
