Fix compilation of GCC 4.9 on SmartOS.

Fix ld-solaris-wrapper never calling ld (since gcc->cc-wrapper refactor).

pkgs/development/compilers/gcc/4.9/default.nix

@@ -293,9 +293,8 @@ stdenv.mkDerivation ({
     ++ (optional stdenv.isDarwin gnused)
     ;
 
-  NIX_LDFLAGS = stdenv.lib.optionalString  stdenv.isSunOS "-lm -ldl";
-
   preConfigure = stdenv.lib.optionalString (stdenv.isSunOS && stdenv.is64bit) ''
+    sed -i -e "s/-lrt//g" libstdc++-v3/configure
     export NIX_LDFLAGS=`echo $NIX_LDFLAGS | sed -e s~$prefix/lib~$prefix/lib/amd64~g`
     export LDFLAGS_FOR_TARGET="-Wl,-rpath,$prefix/lib/amd64 $LDFLAGS_FOR_TARGET"
     export CXXFLAGS_FOR_TARGET="-Wl,-rpath,$prefix/lib/amd64 $CXXFLAGS_FOR_TARGET"
@@ -518,6 +517,7 @@ stdenv.mkDerivation ({
     platforms =
       stdenv.lib.platforms.linux ++
       stdenv.lib.platforms.freebsd ++
+      stdenv.lib.platforms.illumos ++
       optionals (langAda == false) stdenv.lib.platforms.darwin;
   };
 }