storage: refactor metadata lookup
storage: refactor metadata lookup

Prior to this patch, we had the callchains:
external users
  \-> virStorageFileGetMetadataFromFD
      \-> virStorageFileGetMetadataFromBuf
virStorageFileGetMetadataRecurse
  \-> virStorageFileGetMetadataFromFD
      \-> virStorageFileGetMetadataFromBuf

However, a future patch wants to add an additional parameter to
the bottom of the chain, for use by virStorageFileGetMetadataRecurse,
without affecting existing external callers.  Since there is only a
single caller of the internal function, we can repurpose it to fit
our needs, with this patch giving us:

external users
  \-> virStorageFileGetMetadataFromFD
      \-> virStorageFileGetMetadataInternal
virStorageFileGetMetadataRecurse /
  \-> virStorageFileGetMetadataInternal

* src/util/virstoragefile.c (virStorageFileGetMetadataFromFD):
Move most of the guts...
(virStorageFileGetMetadataFromBuf): ...here, and rename...
(virStorageFileGetMetadataInternal): ...to this.
(virStorageFileGetMetadataRecurse): Use internal helper.

trainstack/libvirt,jardasgit/libvirt,cbosdo/libvirt,siboulet/libvirt-openvz,iam-TJ/libvirt,zhlcindy/libvirt-1.1.4-maintain,VenkatDatta/libvirt,siboulet/libvirt-openvz,taget/libvirt,olafhering/libvirt,taget/libvirt,libvirt/libvirt,cbosdo/libvirt,crobinso/libvirt,VenkatDatta/libvirt,zippy2/libvirt,VenkatDatta/libvirt,zhlcindy/libvirt-1.1.4-maintain,libvirt/libvirt,elmarco/libvirt,jardasgit/libvirt,nertpinx/libvirt,libvirt/libvirt,elmarco/libvirt,jfehlig/libvirt,rlaager/libvirt,jfehlig/libvirt,agx/libvirt,elmarco/libvirt,nertpinx/libvirt,cbosdo/libvirt,eskultety/libvirt,datto/libvirt,crobinso/libvirt,iam-TJ/libvirt,trainstack/libvirt,zippy2/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,zhlcindy/libvirt-1.1.4-maintain,zippy2/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,andreabolognani/libvirt,trainstack/libvirt,trainstack/libvirt,elmarco/libvirt,taget/libvirt,nertpinx/libvirt,jardasgit/libvirt,siboulet/libvirt-openvz,andreabolognani/libvirt,agx/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,rlaager/libvirt,olafhering/libvirt,taget/libvirt,trainstack/libvirt,shugaoye/libvirt,agx/libvirt,trainstack/libvirt,datto/libvirt,elmarco/libvirt,nertpinx/libvirt,zippy2/libvirt,zhlcindy/libvirt-1.1.4-maintain,eskultety/libvirt,shugaoye/libvirt,iam-TJ/libvirt,agx/libvirt,crobinso/libvirt,nertpinx/libvirt,iam-TJ/libvirt,olafhering/libvirt,shugaoye/libvirt,jardasgit/libvirt,trainstack/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,agx/libvirt,libvirt/libvirt,iam-TJ/libvirt,eskultety/libvirt,jfehlig/libvirt,iam-TJ/libvirt,rlaager/libvirt,VenkatDatta/libvirt,datto/libvirt,datto/libvirt,eskultety/libvirt,iam-TJ/libvirt,andreabolognani/libvirt,rlaager/libvirt,andreabolognani/libvirt,zhlcindy/libvirt-1.1.4-maintain,shugaoye/libvirt,olafhering/libvirt,fabianfreyer/libvirt,taget/libvirt,eskultety/libvirt,crobinso/libvirt,rlaager/libvirt,siboulet/libvirt-openvz,datto/libvirt,siboulet/libvirt-openvz,cbosdo/libvirt,cbosdo/libvirt