[OE-core] Warnings from autotools_copy_aclocals()

[Andre McCurdy]

Does anyone else see these type of warnings from
autotools_copy_aclocals()? I don't remember exactly when they started
(a few months ago at least, maybe more).

  WARNING: gmp-4.2.1-r0 do_configure:
/.../build-dcx960-debug/tmp/sstate-control/manifest-dcx960-debug-glibc-initial.populate_sysroot
not found
  WARNING: gmp-4.2.1-r0 do_configure:
/.../build-dcx960-debug/tmp/sstate-control/manifest-dcx960-debug-libgcc-initial.populate_sysroot
not found