Can you check if the firefox 57.04 trusty , the working one shows "-march=armv7-a -mfloat-abi=hard -mfpu=vfpv3-d16" in about:buildconfig ?
I'm thinking that "-march=armv7-a -mfloat-abi=hard -mfpu=vfpv3-d16" are automaticaly added when you build something with gcc in Ubuntu armhf .
Can you check if the firefox 57.04 trusty , the working one shows "-march=armv7-a -mfloat-abi=hard -mfpu=vfpv3-d16" in about:buildconf ig ?
I'm thinking that "-march=armv7-a -mfloat-abi=hard -mfpu=vfpv3-d16" are automaticaly added when you build something with gcc in Ubuntu armhf .