usual.m4: INSTALL - use absolute path
usual.m4: INSTALL - use absolute path

rabbitt/libusual,mgjv/libusual,ifduyue/libusual,ifduyue/libusual,markokr/libusual,mgjv/libusual,markokr/libusual,ifduyue/libusual,rabbitt/libusual,markokr/libusual,ifduyue/libusual,markokr/libusual,mgjv/libusual,mgjv/libusual,rabbitt/libusual,rabbitt/libusual