use config.json in makefiles

Makefile

@@ -201,8 +201,12 @@ build: submodules runtime
 fast-build: submodules runtime
 	@${STACK} build --fast ${STACKFLAGS}
 
+.PHONY: configure
+configure:
+	config/configure.sh
+
 .PHONY: runtime
-runtime:
+runtime: configure
 	cd runtime && make
 
 # -- Install

runtime/Makefile

@@ -7,12 +7,20 @@ all: juvix_c juvix_rust
 # 2024-09-20: `-j` cannot be used in the juvix_c make invocation because it causes
 # an error in the 'Build Linux static binary workflow'.
 .PHONY: juvix_c
-juvix_c:
-	cd c && $(MAKE) -s
+juvix_c: juvix_c_native juvix_c_wasm
+	cd c && $(MAKE) -s includes
+
+.PHONY: juvix_c_native
+juvix_c_native:
+	cd c && $(MAKE) -s native64 native64-debug
+
+.PHONY: juvix_c_wasm
+juvix_c_wasm:
+	if grep -q '"wasm": true' ../config/config.json; then cd c && $(MAKE) -s wasm32 wasm32-wasi-debug; fi
 
 .PHONY: juvix_rust
 juvix_rust:
-	cd rust/juvix && cargo build && cargo build --release
+	if grep -q '"rust": true' ../config/config.json; then cd rust/juvix && cargo build && cargo build --release; fi
 
 .PHONY: clean
 clean: