build: resolve SCHEME from $(JERBOA_HOME)/.chez/bin/scheme

ober

9c57ca7127f6add3f6c133046533ad10a589e749

diff --git a/Makefile b/Makefile
index f3c041b..ec62891 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
-SCHEME = scheme
-JERBOA_DIR = $(HOME)/mine/jerboa
+JERBOA_DIR ?= $(HOME)/mine/jerboa
+SCHEME ?= $(JERBOA_DIR)/.chez/bin/scheme
 LIBDIRS = lib:$(JERBOA_DIR)/lib
 
 # Chez external FFI libs (for LMDB, DuckDB, etc.)