I found that if -posix switch is used, linker will try to link both posixcrt0.o and crt0.o by a specs file mistake.
the following patch fix that.
--- specs.nextstep3.orig 2001-02-23 06:50:06.000000000 +0800
+++ specs.nextstep3 2013-12-04 21:21:38.503875000 +0800
@@ -24,11 +24,11 @@
*libgcc:
-lgcc
*startfile:
-%{!posix*:%{static:%{pg:-lgcrt0.o}} %{!static:%{pg:-lgcrt0.o}} } %{!pg: %{p:%e-p profiling is no longer supported. Use -pg instead.} %{!p:%{static:-lcrt0.o} %{!static:-lcrt0.o} }} %{posix*:%{pg:-lgposixcrt0.o}%{!pg: %{p:%e-p profiling is no longer supported. Use -pg instead.} %{!p:-lposixcrt0.o}}}
+%{!posix*:%{static:%{pg:-lgcrt0.o}} %{!static:%{pg:-lgcrt0.o}} %{!pg: %{p:%e-p profiling is no longer supported. Use -pg instead.} %{!p:%{static:-lcrt0.o} %{!static:-lcrt0.o} }} } %{posix*:%{pg:-lgposixcrt0.o}%{!pg: %{p:%e-p profiling is no longer supported. Use -pg instead.} %{!p:-lposixcrt0.o}}}
*switches_need_spaces:
*signed_char:
Good to see someone else fiddling with a compiler :-)!