Find libyui when PREFIX is not /usr

dependent libraries expect includes in $PREFIX/include *and*
$PREFIX/include/yui. That went unnoticed while we installed libyui in
/usr, but when we build it all in a different prefix, this problem
appears.
Let examples (in libyui-qt-graph) find libyui-qt outside /usr
Build all packages without installing them to /usr
parallelize make
don't parse a binary file in gtk as text
gtk does not have license headers, skip it