Only jemalloc 3.5.x and 3.6.x have both nallocm() and nallocx(). FreeBSD 10.x has jemalloc-3.4.0 in libc while FreeBSD 11.0 (in development) has jemalloc-3.6.0. So, the build on FreeBSD with MOZ_JEMALLOC3=1 may either fail due to missing nallocx() or not detect nallocm() for MOZ_NATIVE_JEMALLOC the next time system jemalloc in 11.0 is upgraded. In FreeBSD ports I'll switch Firefox 37.0 from MOZ_NATIVE_JEMALLOC to --enable-jemalloc, still with MOZ_JEMALLOC3=1. Not point sticking to old system jemalloc and fighting regressions from missing junk:free, etc.  how-to: https://svnweb.freebsd.org/base/head/contrib/jemalloc/FREEBSD-upgrade?view=markup
Created attachment 8541796 [details] [diff] [review] fix NPOTB. It'll disable MOZ_NATIVE_JEMALLOC on FreeBSD 10.x.