Add Darwin toolset, from Christopher Currie.

[SVN r19851]

src/tools/darwin.jam

@@ -0,0 +1,40 @@
+#  Copyright (C) Christopher Currie 2003. Permission to copy, use,
+#  modify, sell and distribute this software is granted provided this
+#  copyright notice appears in all copies. This software is provided
+# "as is" without express or implied warranty, and with no claim as to
+#  its suitability for any purpose.
+
+#  Please see http://article.gmane.org/gmane.comp.lib.boost.build/3389/
+#  for explanation why it's a separate toolset.
+
+import toolset : flags ;
+
+toolset.register darwin ;
+toolset.inherit darwin : gcc ;
+
+rule init ( )
+{
+
+}
+
+flags darwin.link.dll OPTIONS : -Wl,-dynamic -nostartfiles -Wl,-dylib -Wl,-ldylib1.o ;
+
+actions link bind LIBRARIES
+{
+    $(NAME:E=g++) $(OPTIONS) -L"$(LINKPATH)" -o "$(<)" "$(>)" "$(LIBRARIES)" -l$(FINDLIBS-SA) -l$(FINDLIBS-ST)
+}
+
+actions link.dll bind LIBRARIES
+{
+    ld -dynamic -m -r -d -o "$(<:S=.lo)" "$(>)" \
+    && \
+    $(NAME:E=g++) $(OPTIONS) -L"$(LINKPATH)" -o "$(<)" "$(<:S=.lo)" "$(LIBRARIES)" -l$(FINDLIBS-SA) -l$(FINDLIBS-ST) \
+    && \
+    rm -f "$(<:S=.lo)"
+}
+
+actions piecemeal archive
+{
+    ar -r -s $(ARFLAGS) "$(<:T)" "$(>:T)"
+}
+