Add a script to extract VSS SDK headers on POSIX system

VSS SDK(*) setup.exe is only runnable on Windows. This adds a script
to extract VSS SDK headers on POSIX-systems using msitools.

  * http://www.microsoft.com/en-us/download/details.aspx?id=23490

From: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

scripts/extract-vsssdk-headers

@@ -0,0 +1,35 @@
+#! /bin/bash
+
+# extract-vsssdk-headers
+# Author: Paolo Bonzini <pbonzini@redhat.com>
+
+set -e
+if test $# != 1 || ! test -f "$1"; then
+  echo 'Usage: extract-vsssdk-headers /path/to/setup.exe' >&2
+  exit 1
+fi
+
+if ! command -v msiextract > /dev/null; then
+  echo 'msiextract not found. Please install msitools.' >&2
+  exit 1
+fi
+
+if test -e inc; then
+  echo '"inc" already exists.' >&2
+  exit 1
+fi
+
+# Extract .MSI file in the .exe, looking for the OLE compound
+# document signature.  Extra data at the end does not matter.
+export LC_ALL=C
+MAGIC=$'\xd0\xcf\x11\xe0\xa1\xb1\x1a\xe1'
+offset=$(grep -abom1 "$MAGIC" "$1" | sed -n 's/:/\n/; P')
+tmpdir=$(mktemp -d)
+trap 'rm -fr -- "$tmpdir" vsssdk.msi' EXIT HUP INT QUIT ALRM TERM
+tail -c +$(($offset+1)) -- "$1" > vsssdk.msi
+
+# Now extract the files.
+msiextract -C $tmpdir vsssdk.msi
+mv "$tmpdir/Program Files/Microsoft/VSSSDK72/inc" inc
+echo 'Extracted SDK headers into "inc" directory.'
+exit 0