BuildSystem: Fix bugs in new build system

I had not tested the new build system with clean toolchain build
but it seems to work now.

toolchain/grub-uefi.cfg

@@ -0,0 +1,26 @@
+insmod part_gpt
+set root=(hd0,gpt2)
+
+menuentry "banan-os" {
+	multiboot2 /boot/banan-os.kernel root=/dev/sda2
+}
+
+menuentry "banan-os (no serial)" {
+	multiboot2 /boot/banan-os.kernel root=/dev/sda2 noserial
+}
+
+menuentry "banan-os (only serial)" {
+	multiboot2 /boot/banan-os.kernel root=/dev/sda2 console=ttyS0
+}
+
+menuentry "banan-os (no apic)" {
+	multiboot2 /boot/banan-os.kernel root=/dev/sda2 noapic
+}
+
+menuentry "banan-os (no apic, no serial)" {
+	multiboot2 /boot/banan-os.kernel root=/dev/sda2 noapic noserial
+}
+
+menuentry "banan-os (no apic, only serial)" {
+	multiboot2 /boot/banan-os.kernel root=/dev/sda2 noapic console=ttyS0
+}