Reverting to continue using GNU.

Makefile

@@ -17,18 +17,17 @@
 # General options
 TARGET=i686
 ARCH=$(shell echo $(TARGET) | sed s/i.86/x86/)
-CROSSFLAGS=--target=$(TARGET)-pc-none-elf -march=$(TARGET)
 # Assembly options
-AS=nasm
-AFLAGS=-felf32 -Isrc/kernel/arch/$(ARCH)/ -Isrc/
+AS=i686-elf-as
+AFLAGS=
 # C options
-CC=clang
+CC=i686-elf-gcc
 CFLAGS?=-O0 -g
-CFLAGS:=$(CFLAGS) $(CROSSFLAGS) -std=c99 -ffreestanding -fno-builtin -nostdlibinc -Wall -Wextra -Isrc/
+CFLAGS:=$(CFLAGS) -std=gnu99 -ffreestanding -Wall -Wextra -Isrc/
 # Linker options
 LDFLAGS?=-O0
-LDFLAGS:=$(LDFLAGS) $(CROSSFLAGS) -ffreestanding -nostdlib
-LIBS=
+LDFLAGS:=$(LDFLAGS) -ffreestanding -nostdlib
+LIBS=-lgcc
 
 # Binary variables
 OBJS=src/kernel/arch/$(ARCH)/boot.o src/kernel/kernel.o src/kernel/arch/$(ARCH)/tty.o