/sbin/fxload in fxload-2008_10_13-8.fc28.x86_64 is not linked with the standard Fedora linker flags (LDFLAGS) from redhat-rpm-config. Simply injecting LDFLAGS from the RPM spec file is not enough because the package makefile appears to ignore LDFLAGS. See https://src.fedoraproject.org/rpms/redhat-rpm-config/blob/master/f/buildflags.md for information on RPM macros and environment variables provided by the build environment.
Fixed in fxload-2008_10_13-10.fc29.