pkgs/development/libraries/crypto++: fixed build impurity

* Don't build with "-march=native", because the generated binaries
   won't work reliably on systems with a different CPU. Instead,
   "--march=i686" is used on x86, and "--march=nocona" an x86_64.
   Otherwise, "--march" remains unset.

 * Compile with -O3 instead of -O2. This code is performance-critical.

 * Don't build with '-g'.

svn path=/nixpkgs/trunk/; revision=22785

pkgs/development/libraries/crypto++/default.nix

@@ -24,6 +24,17 @@ stdenv.mkDerivation rec {
     sourceRoot="$PWD/${name}"
   '';
 
+  cxxflags = if stdenv.isi686 then "-march=i686" else
+             if stdenv.isx86_64 then "-march=nocona" else
+             "";
+
+  configurePhase = ''
+    sed -i GNUmakefile \
+      -e 's|-march=native|${cxxflags}|g' \
+      -e 's|-mtune=native||g' \
+      -e '/^CXXFLAGS =/s|-g -O2|-O3|'
+  '';
+
   # Deal with one of the crappiest build system around there.
   buildPhase = ''
     # These guys forgot a file or something.

pkgs/top-level/all-packages.nix

@@ -3761,7 +3761,6 @@ let
   };
 
   cryptopp = import ../development/libraries/crypto++ {
-    # SIDE-EFFECT WARNING: crypto++-5.6.0 is compiled with "-O2 -march=native -mtune=native".
     inherit fetchurl stdenv unzip libtool;
   };