Merge pull request #18504 from mikedn/comp-small

Make Compiler and CodeGen objects smaller

diff --cc src/jit/compiler.h
Simple merge

diff --cc src/jit/hwintrinsiccodegenxarch.cpp
Simple merge

diff --cc src/jit/importer.cpp
Simple merge

diff --cc src/jit/lsra.cpp
Simple merge

diff --cc src/jit/simd.cpp
Simple merge