Add build script

This commit adds a build script for the loader partition. Currently,
it is very simplistic, but it works for assembling the entry.asm,
which in turn includes all other files.

i386/loader/build.bash

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+
+INVOCATION_PATH=$(pwd)
+cd $(dirname $0)
+SCRIPT_PATH=$(pwd)
+
+# Assemble the loader
+nasm -fbin -o $SCRIPT_PATH/loader.bin -I $SCRIPT_PATH/src-asm \
+    $SCRIPT_PATH/src-asm/entry.asm