Config: Disable parallel builds for Cargo on riscv64

There seems to be some problem where Cargo deadlocks during the build
when running on mutliple cores simulteneously.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

lfs/Config

@@ -209,9 +209,15 @@ CARGO = \
 	--offline
 
 CARGO_OPTIONS = \
-	$(MAKETUNING) \
 	-Z avoid-dev-deps
 
+# Cargo dealocks on riscv64 when building on multiple cores at the same time
+ifeq "$(BUILD_ARCH)" "riscv64"
+	CARGO_OPTIONS += -j1
+else
+	CARGO_OPTIONS += $(MAKETUNING)
+endif
+
 define CARGO_PREPARE
 	mkdir -p $(CARGO_PATH) && \
 	echo "$${CARGO_CONFIG}" > $(CARGO_PATH)/config && \