Fix python to build with newlib.

libraries/python/nacl-python.sh

 #!/bin/bash
 # Copyright (c) 2013 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 source pkg_info
 source ../../build_tools/common.sh
 
 EXECUTABLES=python.nexe
 # Currently this package only builds on linux.
 # The build relies on certain host binaries and pythong's configure
 # requires us to sett --build= as well as --host=.
-EXTRA_CONFIGURE_ARGS="--disable-ipv6 --with-suffix=.nexe --build=x86_64-linux-gnu"
-export MAKEFLAGS="PGEN=../build-nacl-host/Parser/pgen"
 HERE=$(cd "$(dirname "$BASH_SOURCE")" ; pwd)
 
 BuildHostPython() {
   ChangeDir ${NACL_PACKAGES_REPOSITORY}/${PACKAGE_DIR}
   MakeDir build-nacl-host
   ChangeDir build-nacl-host
   LogExecute ../configure
   LogExecute make -j${OS_JOBS} python Parser/pgen
 }
 
 CustomConfigureStep() {
   BuildHostPython
   export CROSS_COMPILE=true
   # We pre-seed configure with certain results that it cannot determine
   # since we are doing a cross compile.  The $CONFIG_SITE file is sourced
   # by configure early on.
+  EXTRA_CONFIGURE_ARGS+=" --disable-ipv6"

[Mark Seaborn, 2013/07/12 19:47:29]

Can you comment why this is needed?  What fails without this?  Does this disable
all networking usage, or just IPv6 and not IPv4?

[Sam Clegg, 2013/07/12 21:54:29]

I'm just moving this from above, but you are right that this deserves a comment.

+  EXTRA_CONFIGURE_ARGS+=" --with-suffix=.nexe"
+  EXTRA_CONFIGURE_ARGS+=" --build=x86_64-linux-gnu"
+  export MAKEFLAGS="PGEN=../build-nacl-host/Parser/pgen"
   export CONFIG_SITE=${HERE}/config.site
+  export LIBS="-lc -lnosys"

[Mark Seaborn, 2013/07/12 19:47:29]

"-lc" should be implicit.  Can you omit that and just use "-lnosys"?

[Sam Clegg, 2013/07/12 21:54:29]

I found that I needed to put -lnosys after -lc (which means I need to be
explicit like this).  The problem occurs when a function libc is the first users
of a symbol in nosys.  If nosys has already been passed over by the linker the
symbol will not be found.  

In this case the error I get without putting -lc first is:

{{{
/home/sbc/nacl_sdk/pepper_canary/toolchain/linux_x86_newlib/bin/../lib/gcc/x86_64-nacl/4.4.3/../../../../x86_64-nacl/lib/../lib64/libcrt_common.a(lib_a-execv.o):
In function `execv':
execv.c:(.text+0xd): undefined reference to `_execve'
}}}

   DefaultConfigureStep
 }
 
 CustomTestStep() {
   WriteSelLdrScript python python.nexe
 }
 
 CustomPackageInstall() {
   DefaultPreInstallStep
   DefaultDownloadStep
   DefaultExtractStep
   DefaultPatchStep
   CustomConfigureStep
   DefaultBuildStep
   DefaultTranslateStep
   DefaultValidateStep
   CustomTestStep
   DefaultInstallStep
   DefaultCleanUpStep
 }
 
 CustomPackageInstall
 exit 0