message: Add env var to use ssytem libffi
diff: @@ -47,6 +47,7 @@ endif
  # If it's an aarch64/arm64 chip
  # Using filter as a logical OR
  # https://stackoverflow.com/questions/7656425/makefile-ifeq-logical-or
  +use_system_ffi =
  ifneq (,$(filter $(ARCH),aarch64 arm64))
  test_compilers_engines += cranelift-jit
  ifneq (, $(findstring llvm,$(compilers)))
  @@ -54,8 +55,18 @@ ifneq (,$(filter $(ARCH),aarch64 arm64))
  endif
  # if we are in macos arm64, we use the system libffi for the capi
  ifeq ($(UNAME_S), Darwin)
  - capi_default_features := --features system-libffi
  + use_system_ffi = yes
  + endif
  +endif
  +
  +# if the user has set the `WASMER_CAPI_USE_SYSTEM_LIBFFI` var to 1 also
  +# use the system libffi.
  +ifeq ($(WASMER_CAPI_USE_SYSTEM_LIBFFI), 1)
  + use_system_ffi = yes
  endif
  +
  +ifdef use_system_ffi
  + capi_default_features := --features system-libffi
  endif
  compilers := $(filter-out ,$(compilers))
  