m4/multiarch.m4's gl_MULTIARCH macro defines AA_APPLE_UNIVERSAL_BUILD, but as far as I can tell nobody uses that symbol. I propose that we remove it, as unnecessary. (I'm trying to put Emacs src/config.h on a diet and this would remove one more unnecesary symbol from Emacs.)
Autoconf's AC_C_BIGENDIAN defines AC_APPLE_UNIVERSAL_BUILD in order to get WORDS_BIGENDIAN right, and I expect this was copied to gnulib and renamed at some point, but that the need for the symbol in gnulib (if there ever was one) has gone away.
