this package uses LDFLAGS for both gcc and ld for example, I set LDFLAGS as LDFLAGS="-Wl,-O,1,-z,combreloc" in /etc/make.conf, and the building process fails setting LDFLAGS to "-O 1 -z combreloc" would also fail the build during the configure phase, because LDFLAGS would be directly appended to gcc options perhaps this is an issue broader than just emacs build
LDFLAGS="-Wl,-O,....." is not valid for now, stop doing it see Bug 65002