cons: fix for multiple include dirs returned by xml2-config (#497)

xml2-config --cflags may return multiple paths in which case cons
expects them to be separated by ':'

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Co-authored-by: Dmitry Kalinkin <[email protected]>

Author: plexoos

mgr/ConsDefs.pm

@@ -983,7 +983,8 @@
 
     $XMLINCDIR = `$xml --cflags`;
     chomp($XMLINCDIR);
-    $XMLINCDIR =~ s/-I//;
+    $XMLINCDIR =~ s/ -I/:/g;
+    $XMLINCDIR =~ s/-I//g;
     my $XML  = `$xml --libs`; # die "$XML\n";
     my(@libs)= split(" ", $XML);