Merge branch 'xargo-to-cargo' into 'master'

Switch kernel builds away from using xargo

See merge request redox-os/redox!1255

mk/config.mk

@@ -38,7 +38,6 @@ endif
 ROOT=$(CURDIR)
 export RUST_COMPILER_RT_ROOT=$(ROOT)/rust/src/llvm-project/compiler-rt
 export RUST_TARGET_PATH=$(ROOT)/kernel/targets
-export XARGO_HOME=$(ROOT)/build/xargo
 export XARGO_RUST_SRC=$(ROOT)/rust/src
 
 ## Kernel variables

mk/kernel.mk

@@ -2,19 +2,19 @@ build/libkernel.a: kernel/Cargo.lock kernel/Cargo.toml kernel/src/* kernel/src/*
 	export PATH="$(PREFIX_PATH):$$PATH" && \
 	export INITFS_FOLDER=$(ROOT)/build/initfs && \
 	cd kernel && \
-	xargo rustc --lib --target $(KTARGET) --release -- -C soft-float -C debuginfo=2 -C lto --emit link=../$@
+	cargo rustc --lib --target=$(ROOT)/kernel/targets/$(KTARGET).json --release -Z build-std=core,alloc -- -C soft-float -C debuginfo=2 -C lto --emit link=../$@
 
 build/libkernel_coreboot.a: kernel/Cargo.toml kernel/src/* kernel/src/*/* kernel/src/*/*/* kernel/src/*/*/*/* build/initfs_coreboot.tag
 	export PATH="$(PREFIX_PATH):$$PATH" && \
 	export INITFS_FOLDER=$(ROOT)/build/initfs_coreboot && \
 	cd kernel && \
-	xargo rustc --lib --target $(KTARGET) --release --features live -- -C soft-float -C debuginfo=2 -C lto --emit link=../$@
+	cargo rustc --lib --target=$(ROOT)/kernel/targets/$(KTARGET).json --release --features live -Z build-std=core,alloc -- -C soft-float -C debuginfo=2 -C lto --emit link=../$@
 
 build/libkernel_live.a: kernel/Cargo.toml kernel/src/* kernel/src/*/* kernel/src/*/*/* kernel/src/*/*/*/* build/initfs_live.tag
 	export PATH="$(PREFIX_PATH):$$PATH" && \
 	export INITFS_FOLDER=$(ROOT)/build/initfs_live && \
 	cd kernel && \
-	xargo rustc --lib --target $(KTARGET) --release --features live -- -C soft-float -C debuginfo=2 -C lto --emit link=../$@
+	cargo rustc --lib --target=$(ROOT)/kernel/targets/$(KTARGET).json --release --features live -Z build-std=core,alloc -- -C soft-float -C debuginfo=2 -C lto --emit link=../$@
 
 build/kernel: kernel/linkers/$(ARCH).ld build/libkernel.a
 	export PATH="$(PREFIX_PATH):$$PATH" && \

mk/prefix.mk

@@ -28,6 +28,8 @@ $(PREFIX)/relibc-install: $(ROOT)/relibc | $(PREFIX)/rust-install
 	cd "$@.partial" && $(PREFIX_STRIP)
 	touch "$@.partial"
 	mv "$@.partial" "$@"
+	mkdir $@/lib/rustlib/src
+	ln -s $(ROOT)/rust $@/lib/rustlib/src
 
 $(PREFIX)/relibc-install.tar.gz: $(PREFIX)/relibc-install
 	tar \