lang/erlang: temporarily hide DTRACE option on aarch64

obj/aarch64-portbld-freebsd11.0/opt/smp/beam_emu.o: In function `process_main':
beam/beam_emu.c:(.text+0x1ec): undefined reference to `dtraceenabled_erlang_processscheduled'
beam/beam_emu.c:(.text+0x3c4): undefined reference to `dtrace_erlang___processscheduled'
beam/beam_emu.c:(.text+0x3274): undefined reference to `dtraceenabled_erlang___localfunctionentry'
beam/beam_emu.c:(.text+0x32b0): undefined reference to `dtrace_erlang_localfunctionentry'
beam/beam_emu.c:(.text+0x3318): undefined reference to `dtraceenabled_erlang_localfunctionentry'
[...]

PR: 214556 (maybe unrelated)
Reported by: pkg-fallout