bintools-wrapper, cc-wrapper: don't add targetPrefix the second time

... binutils and gcc add it already anyway.

Without this it's easy to get cross-toolchain paths longer than 256
chars and nix-daemon will then fail to commit them to /nix/store on XFS.

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

@@ -74,7 +74,7 @@ in
 
 stdenv.mkDerivation {
   name = targetPrefix
-    + (if name != "" then name else "${bintoolsName}-wrapper")
+    + (if name != "" then name else stdenv.lib.removePrefix targetPrefix "${bintoolsName}-wrapper")
     + (stdenv.lib.optionalString (bintools != null && bintoolsVersion != "") "-${bintoolsVersion}");
 
   preferLocalBuild = true;

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

@@ -71,7 +71,7 @@ assert nativePrefix == bintools.nativePrefix;
 
 stdenv.mkDerivation {
   name = targetPrefix
-    + (if name != "" then name else "${ccName}-wrapper")
+    + (if name != "" then name else stdenv.lib.removePrefix targetPrefix "${ccName}-wrapper")
     + (stdenv.lib.optionalString (cc != null && ccVersion != "") "-${ccVersion}");
 
   preferLocalBuild = true;