title: setting make variable (FreeBSD 9.3) on if condition
body: <p>I am trying to redo part of the Makefile we use for building NAS, I am having trouble setting <code>SEQUENCE</code> to <code>${TRAIN}-${BUILD_TIMESTAMP}</code> when update server is defined. I use the following command to build.</p>
  
  <p><code>env UPDATE_INTERNAL=yes build/release.sh NAS yes</code></p>
  
  <pre><code>ENV_SETUP+= NANO_LABEL=${NANO_LABEL}
  ENV_SETUP+= VERSION=${VERSION}
  ENV_SETUP+= BUILD_TIMESTAMP=${BUILD_TIMESTAMP}
  ENV_SETUP+= SEQUENCE=${NANO_LABEL}-${RELEASE_IDENTIFIER}-RELEASE
  ENV_SETUP+= TRAIN=${TRAIN}
  ENV_SETUP+= UPDATE_USER=${UPDATE_USER}
  ENV_SETUP+= UPDATE_HOST=${UPDATE_HOST}
  ENV_SETUP+= FREENAS_KEYFILE=${FREENAS_KEYFILE}
  .if exists(ChangeLog)
  ENV_SETUP+= CHANGELOG=ChangeLog
  .endif
  
  .if defined(UPDATE_INTERNAL)
  SEQUENCE=${TRAIN}-${BUILD_TIMESTAMP}
  UPDATE_USER?=vb-int
  UPDATE_HOST?=vb-update-int.yyyyy.xxxxx.com
  POST_TO_DOWNLOAD=no
  .else
  UPDATE_USER?=xxx
  UPDATE_HOST?=update.something.org
  POST_TO_DOWNLOAD=yes
  .endif
  </code></pre>
  
  <p>I am editing to include o/p of the command
  <code>
  env _KEY=set NANO_LABEL=NAS VERSION=9.3-STABLE BUILD_TIMESTAMP=201602092045 SEQUENCE=NAS-9.3.2-RELEASE TRAIN=NAS-9.3-STABLE UPDATE_USER=......
  </code></p>