Add error on missing ccallable

[vchuravy]

While mucking about I observed that a @ccallable added to Base,
will not be exported from the .so.

readelf -s usr/lib/julia/sys-debug-o.a | grep __rts
...
7680: 0000000000000000   353 FUNC    GLOBAL HIDDEN     2 __rts_enter

See how it is marked HIDDEN.

Interestingly enough this works from a pkgimg.

nm -D ~/.julia/compiled/v1.11/TestPkg/SjF8z_v2vZq.so 
0000000000001a00 T f

I suspect @pchintalapudi multi-versioning work is to blame.

cc: @KristofferC and @maleadt since this might break some package compiler use-cases.

[vtjnash]

  f35014 not found in sysimg

[vchuravy]

  f35014 not found in sysimg

Yup, this is making sure that the test fails instead of falsely succeeding. Before we would fail to find the exported symbol and just for pkg.images, but not the sys image, recreate the entry point while loading the package.

This aligns the code paths for both system image and package image, so that we can test the fix :)