Use LINK_PLUGIN_SPEC on Darwin (PR target/48245)

[Rainer Orth]

When developing the patch to use the linker plugin only if the (plugin)
linker supports it, I had neglected to check for targets that defined
their own version of LD_COMMAND_SPEC.  Of course, this couldn't go
unpunished, since there are two of them:

* Darwin has its own version in config/darwin.h.  This is updated by the
  following patch.

* The only other affected target is DJGPP (i[34567]86-pc-msdosdjgpp*),
  but config/i386/djgpp.has no provisions for LTO at all, so I'm not
  touching that.

The (almost obvious) patch was tested by Iain on *-darwin9 and by
Dominique on x86_64-darwin10.

Approved by Mike in the PR, installed on mainline.

	Rainer


2011-03-26  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
	    Iain Sandoe  <iains@gcc.gnu.org>

	PR target/48245
	* config/darwin.h (LINK_COMMAND_SPEC_A): Use LINK_PLUGIN_SPEC.

diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -184,8 +184,9 @@ extern GTY(()) int darwin_ms_struct;
 
 #define LINK_COMMAND_SPEC_A \
    "%{!fdump=*:%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
-    %(linker) \
-    %{flto*:%<fcompare-debug*} \
+    %(linker)" \
+    LINK_PLUGIN_SPEC \
+    "%{flto*:%<fcompare-debug*} \
     %{flto*} \
     %l %X %{s} %{t} %{Z} %{u*} \
     %{e*} %{r} \

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University