bus-message: fix skipping of array fields in !gvariant messages
    
    We copied part of the string into a buffer that was off by two.
    If the element signature had length one, we'd copy 0 bytes and crash when
    looking at the "first" byte. Otherwise, we would crash because strncpy would
    not terminate the string.
    
    (cherry picked from commit 73777ddba5100fe6c0791cd37a91f24a515f3202)
    
    Resolves: #1696224
    
    patch_name: 0172-bus-message-fix-skipping-of-array-fields-in-gvariant.patch
    present_in_specfile: true
    location_in_specfile: 172
    squash_commits: true