/usr/bin/foomatic-combo-xml and /usr/bin/foomatic-perl-data in foomatic-4.0.12-21.fc28.x86_64 have not been linked with the standard Fedora linker flags (LDFLAGS) from redhat-rpm-config:

gcc -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -mcet -fcf-protection -o foomatic-combo-xml foomatic-combo-xml.c

gcc -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -mcet -fcf-protection -I/usr/include/libxml2 -o foomatic-perl-data foomatic-perl-data.c -lxml2 -lz -llzma -lm -ldl

CFLAGS are there, but LDFLAGS are missing.

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.