Build fails in RHEL8 "could not determine what C.RTLD_NEXT refers to"

I get the error: -

./transaction.go:409:55: could not determine what C.RTLD_NEXT refers to

RTLD_NEXT is inside a #ifdef __USE_GNU block in dlfcn.h, which causes the build to fail, as this is not defined
This in AlmaLinux release 8.10 (Cerulean Leopard), binary compatible with RHEL

this can be fixed by adding

#define _GNU_SOURCE

I'll raise a PR