Add build scripts

compile

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+CC=clang
+CFLAGS="-g -Wall -Werror "
+
+XORSHIFT_SRC="xorshift.c ppm.c"
+XORSHIFT_OUT=xorshift
+
+(set -x ; $CC $CFLAGS $XORSHIFT_SRC -o $XORSHIFT_OUT)