[Libguestfs] No rule to make target `guestfs.pod', needed by `guestfs.3' in po-docs/ja

[Jim Meyering]

FYI, I hit this failure:

  make[3]: Entering directory `/h/j/w/co/libguestfs/po-docs/ja'
  make[3]: *** No rule to make target `guestfs.pod', needed by `guestfs.3'.  Stop.
  make[3]: Leaving directory `/h/j/w/co/libguestfs/po-docs/ja'

guestfs.pod is in src/.
I'll investigate later, if needed.