Use LLVM linker, Dockerfile now works without GCC

kernel/Makefile

@@ -1,4 +1,5 @@
 cc := clang
+ld := ld.lld
 o :=
 c :=
 ldflags :=
@@ -12,7 +13,7 @@ include make/src.mk
 all: build/kernel.elf
 
 build/kernel.elf: $(o)
-	$(cc) -o $@ $(ldflags) -T $(platform)/link.ld $^
+	$(ld) -o $@ $(ldflags) -T $(platform)/link.ld $^
 
 %.o: %.c
 	$(cc) -c -o $@ $(cflags) $<

kernel/amd64/flags.mk

@@ -1,4 +1,4 @@
-cflags += --target=x86_64-pc-none-elf \
+cflags += --target=x86_64-unknown-unknown-elf \
 					-mno-sse \
 					-mno-sse2 \
 					-mno-avx \
@@ -7,5 +7,4 @@ cflags += --target=x86_64-pc-none-elf \
 					-mno-red-zone \
 					-fno-omit-frame-pointer
 
-ldflags += --target=x86_64-pc-none-elf \
-					 -Wl,-zmax-page-size=0x1000
+ldflags += -zmax-page-size=0x1000

kernel/generic/flags.mk

@@ -23,18 +23,11 @@ ifeq ($(buildtype),release)
 	cflags += -ffunction-sections -fdata-sections -Oz
 endif
 
-ldflags += -ffreestanding \
-					 -nostdlib \
-					 -fno-builtin \
-					 -fuse-ld=lld \
-					 -static
-
-ifeq ($(buildtype),debug)
-	ldflags += -g
-endif
+ldflags += --nostdlib \
+					 --static
 
 ifeq ($(buildtype),release)
-	ldflags += -Wl,--gc-sections \
-						 -Wl,--strip-all \
-						 -flto
+	ldflags += --gc-sections \
+						 --strip-all \
+						 -O3
 endif