Fix compilation of GCC 4.9 on SmartOS. Fix ld-solaris-wrapper never calling ld (since gcc->cc-wrapper refactor).

pkgs/build-support/cc-wrapper/default.nix

···
     + optionalString (stdenv.isSunOS && nativePrefix != "") ''
       # Solaris needs an additional ld wrapper.
       ldPath="${nativePrefix}/bin"
-      ld="$out/bin/ld-solaris"
+      exec="$ldPath/ld"
       wrap ld-solaris ${./ld-solaris-wrapper.sh}
     '')
 

pkgs/build-support/cc-wrapper/ld-solaris-wrapper.sh

···
 # I've also tried adding -z direct and -z lazyload, but it gave too many problems with C++ exceptions :'(
 # Also made sure libgcc would not be lazy-loaded, as suggested here: https://www.illumos.org/issues/2534#note-3
 #   but still no success.
-cmd="@prog@ -z ignore"
+cmd="@ld@ -z ignore"
 
 args=("$@");
 

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

···
     ++ (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"
···
     platforms =
       stdenv.lib.platforms.linux ++
       stdenv.lib.platforms.freebsd ++
+      stdenv.lib.platforms.illumos ++
       optionals (langAda == false) stdenv.lib.platforms.darwin;
   };
 }