userland: replace legacy cc with native TCC and vendor submodule

src/userland/cli/third_party/tcc/build_libtcc1.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+CC=x86_64-elf-gcc
+AR=x86_64-elf-ar
+CFLAGS="-O2 -m64 -march=x86-64 -fno-stack-protector -ffreestanding -nostdlib -I. -I./include -I../../../sdk/include"
+
+echo "Building libtcc1.a..."
+$CC $CFLAGS -c lib/libtcc1.c -o libtcc1.o
+$AR rcs libtcc1.a libtcc1.o
+rm libtcc1.o
+echo "Done."