Qt 4.4 incompatibilities fixed


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2054 29e17f8d-cf37-471e-a288-72cc03a76eda
QMAKE_LIBDIR issues


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2058 29e17f8d-cf37-471e-a288-72cc03a76eda
duplicated setting of warn_on removed


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2060 29e17f8d-cf37-471e-a288-72cc03a76eda