message: Report error codes in docs building script
diff: rst2html=rst2html
  +exit_status=0
  for i in ispc ispc_for_gen perfguide faq; do
  $rst2html --template=template.txt --link-stylesheet \
  - --stylesheet-path=css/style.css $i.rst > $i.html
  + --stylesheet-path=css/style.css --exit-status=2 $i.rst > $i.html
  + (( exit_status = exit_status || $? ))
  done
  $rst2html --template=template-perf.txt --link-stylesheet \
  - --stylesheet-path=css/style.css perf.rst > perf.html
  + --stylesheet-path=css/style.css --exit-status=2 perf.rst > perf.html
  +(( exit_status = exit_status || $? ))
  #rst2latex --section-numbering --documentclass=article --documentoptions=DIV=9,10pt,letterpaper ispc.rst > ispc.tex
  #pdflatex ispc.tex
  #/bin/rm -f ispc.aux ispc.log ispc.out ispc.tex
  +
  +[ $exit_status -eq 0 ]
  