use compatible check for dot version

[hector.oron at gmail.com]

From: Hector Oron <hector.oron at collabora.co.uk>

Hello,

  configure uses grep -oP to check for dot version in the following form:
    dot_version=`$DOT -V 2>&1|$GREP -oP '(?<=version\W)@<:@0-9.@:>@*(?=\W(.*))'`
  that is not supported in old grep versions.
  The proposed patch uses equivalent sed form instead.
    dot_version=`$DOT -V 2>&1|$SED -ne 's/.*version \([[0-9.]]*\) .*/\1/p'`

Hector Oron (1):
  configure.ac: use compatible check for dot version

 configure.ac | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

-- 
2.1.4