Bug report: gnucap-default-plugins.so fails to load on Arch Linux (snapshot 2026.03.29)

Hello,

I am writing to report a bug in gnucap snapshot 2026.03.29 on Arch Linux 
x86_64.

## Summary

gnucap fails to load gnucap-default-plugins.so at startup, causing all 
directives (.INCLUDE, .PRINT, .AC, .END, etc.) to be unrecognized.

## Environment

- OS: Arch Linux x86_64.
- gnucap version: snapshot 2026.03.29 (main, core-lib and default 
plugins all matching).
- Installed via AUR package. Also tried gnucap-git and manual build.

## Symptoms

Running `gnucap -b circuit.cir` produces errors like:

   .INCLUDE uA741.model
    ^ ? INCLUDE: no match
   .PRINT AC vdb(4)
    ^ ? PRINT: no match
   .AC DEC 100 20 20k > f1.dat
    ^ ? AC: no match
   .END
    ^ ? END: no match

## Diagnosis

Using strace, I found the following sequence when gnucap attempts to 
load the plugin:

   openat(AT_FDCWD, "/usr/lib/gnucap/gnucap-default-plugins.so", 
O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = -1 ENOTDIR (Not a directory)
   openat(AT_FDCWD, "/usr/lib/gnucap/gnucap-default-plugins.so", 
O_RDONLY|O_CLOEXEC) = 3

The first openat call uses the O_DIRECTORY flag on a .so file, which 
fails with ENOTDIR. Although a second correct openat call follows and 
succeeds (fd=3), the plugin appears not to be initialised properly. All 
directives remain unrecognised throughout the session.

The .so file exists, has correct permissions (755), and all its 
dependencies are satisfied (verified with ldd).

## Steps to reproduce

1. Install gnucap snapshot 2026.03.29 on Arch Linux.
2. Run `gnucap -b <any.cir>` with a standard netlist containing .PRINT, 
.AC, .END, etc.
3. Observe that all directives are reported as unrecognised.

## Additional notes

Manually running `load /usr/lib/gnucap/gnucap-default-plugins.so` in 
interactive mode triggers a segmentation fault with the message "already 
loaded, replacing", suggesting the plugin is being loaded twice or there 
is a conflict during reinitialisation.

Thank you for your time and for maintaining gnucap.

Best regards,
Aniol