add tool to build minimal xilinx toolchains

xilinx_strace_tailor.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+# Copyright Robert Jordens <robert@joerdens.org> 2014,2015
+
+# assuming your xilinx toolchain lives in /opt/Xilinx,
+# run `strace-tailor.sh [synthesis script] [options]`
+# then in your current directory, `opt/Xilinx/*` is the
+# minimal toolchain required for this synthesis script run.
+
+PREFIX=\\/opt\\/Xilinx\\/
+
+strace -e trace=file,process -f -o strace.log $@
+sed -n "s/^.*\"\\(${PREFIX}[^\"]*\\)\".*$/\\1/p" strace.log \
+	| sort | uniq | tr '\n' '\0' \
+	| xargs -0 cp --parent --no-dereference --preserve=all -t .