Fix localfile name if labels are used

I could apply the label "release_1.0" to a super project that contains many sub projects.  If my recipes have SRC_URI's that use that label but grab different sub-folders, than there's a bug where the cached localfile (tar.gz) will not be unique and reused at the wrong times.

SRC_URI = "p4://perforce::1234@//depot/SuperProject/MiniProjectAAA/...;label=release_1.0 \
                     p4://perforce::1234@//depot/SuperProject/MiniProjectBBB/...;label=release_1.0"