Fix syntax-check
    
    Commit c45a30e9 broke syntax-check:
    
    trailing_blank
    src/virt-viewer-window.c:1478:
    maint.mk: found trailing blank(s)
    maint.mk:700: recipe for target 'sc_trailing_blank' failed
    make: *** [sc_trailing_blank] Error 1
    
    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>