Changed variable PKG_CONFIG to PKG_CONFIG_CHECK.  The name PKG_CONFIG is already being used to refer to the pkg-config executable.  Result substitution into PKG_CONFIG was causing a failure during configuration.
Changed variable PKG_CONFIG to PKG_CONFIG_CHECK.  The name PKG_CONFIG
is already being used to refer to the pkg-config executable.  Result
substitution into PKG_CONFIG was causing a failure during configuration.

svn path=/trunk/; revision=5991

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot