break out prop fetching to its own file

etc/makefiles/arduino-cli-prop.mk

@@ -0,0 +1,31 @@
+mkfile_path := $(abspath $(lastword $(MAKEFILE_LIST)))
+mkfile_dir := $(dir $(mkfile_path))
+
+# Make a variable lazily evaluated at first call
+# From https://blog.jgc.org/2016/07/lazy-gnu-make-variables.html
+make-lazy = $(eval $1 = $$(eval $1 := $(value $(1)))$$($1))
+
+system_arduino_cli=$(shell command -v arduino-cli || true)
+
+ifeq ($(system_arduino_cli),) 
+export ARDUINO_CLI ?= $(KALEIDOSCOPE_BIN_DIR)/arduino-cli
+else
+export ARDUINO_CLI ?= $(system_arduino_cli)
+endif
+
+# This is horrible. But because make doesn't really support
+# multi-line variables and we want to cache the full
+# _arduino_props in a variable, which means letting make 
+# split the properties on space, which is what it converts
+# newlines into. To make this go, we we need to replace interior
+# spaces in the variables with something. We chose the fire 
+# emoji, since it accurately represents our feelings on this 
+# state of affairs. Later, when finding props, we need to reverse 
+# this process, turning fire into space.
+_arduino_props = $(shell ${ARDUINO_CLI}  compile --show-properties "$${SKETCH_FILE_PATH}"|perl -p -e"s/ /🔥/g")
+$(call make-lazy,_arduino_props)
+
+_arduino_prop = $(subst $1=,,$(subst 🔥, ,$(filter $1=%,$(_arduino_props))))
+
+# How to use_arduino_prop
+# $(call _arduino_prop,recipe.hooks.sketch.prebuild.2.pattern)

etc/makefiles/arduino-cli.mk

@@ -1,9 +1,6 @@
 mkfile_path := $(abspath $(lastword $(MAKEFILE_LIST)))
 mkfile_dir := $(dir $(mkfile_path))
-
-# Make a variable lazily evaluated at first call
-# From https://blog.jgc.org/2016/07/lazy-gnu-make-variables.html
-make-lazy = $(eval $1 = $$(eval $1 := $(value $(1)))$$($1))
+include $(mkfile_dir)/arduino-cli-prop.mk
 
 export KALEIDOSCOPE_DIR ?= $(abspath $(mkfile_dir)/../..)
 export KALEIDOSCOPE_BIN_DIR ?= $(KALEIDOSCOPE_DIR)/bin
@@ -31,25 +28,7 @@ else
 export ARDUINO_VERBOSE ?= 
 endif
 
-# This is horrible. But because make doesn't really support
-# multi-line variables and we want to cache the full
-# _arduino_props in a variable, which means letting make 
-# split the properties on space, which is what it converts
-# newlines into. To make this go, we we need to replace interior
-# spaces in the variables with something. We chose the fire 
-# emoji, since it accurately represents our feelings on this 
-# state of affairs. Later, when finding props, we need to reverse 
-# this process, turning fire into space.
-_arduino_props = $(shell ${ARDUINO_CLI}  compile --show-properties "$${SKETCH_FILE_PATH}"|perl -p -e"s/ /🔥/g")
-$(call make-lazy,_arduino_props)
-
-_arduino_prop = $(subst $1=,,$(subst 🔥, ,$(filter $1=%,$(_arduino_props))))
-
-# How to use_arduino_prop
-# $(call _arduino_prop,recipe.hooks.sketch.prebuild.2.pattern)
-
 
-#
 .PHONY: configure-arduino-cli install-arduino-core-kaleidoscope install-arduino-core-avr
 .PHONY: all