Make it compile on macOS

Makefile

@@ -10,6 +10,14 @@ assembly_source_files := $(wildcard src/arch/$(arch)/*.asm)
 assembly_object_files := $(patsubst src/arch/$(arch)/%.asm, \
 	build/arch/$(arch)/%.o, $(assembly_source_files))
 
+ifeq ($(shell uname), Linux)
+	prefix :=
+else
+	prefix := x86_64-elf-
+endif
+
+ld := $(prefix)ld
+
 .PHONY: all clean run iso kernel
 
 all: $(kernel)
@@ -18,7 +26,7 @@ clean:
 	@rm -r build
 
 run: $(iso)
-	@qemu-system-x86_64 -cdrom $(iso)
+	@qemu-system-$(arch) -cdrom $(iso)
 
 iso: $(iso)
 
@@ -30,7 +38,7 @@ $(iso): $(kernel) $(grub_cfg)
 	@rm -r build/isofiles
 
 $(kernel): kernel $(rust_os) $(assembly_object_files) $(linker_script)
-	@ld -n --gc-sections -T $(linker_script) -o $(kernel) \
+	@$(ld) -n --gc-sections -T $(linker_script) -o $(kernel) \
 		$(assembly_object_files) $(rust_os)
 
 kernel: