Reduce the number of times we build a host copy of python.

ports/python-host/build.sh

 # 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.
 
 # Use the same patch here as for the destination tree.  This allows us to use
 # the same tree for both, although some care should be taken to note that our
 # DYNLOAD will be different between the two builds.
-BUILD_DIR=${WORK_DIR}/build-nacl-host
+BUILD_DIR=${WORK_DIR}/build_host
 
 ConfigureStep() {
-  MakeDir ${BUILD_DIR}
-  ChangeDir ${BUILD_DIR}
   # Reset CFLAGS and LDFLAGS when configuring the host
   # version of python since they hold values designed for
   # building for NaCl.  Note that we are forcing 32 bits here so
   # our generated modules use Py_ssize_t of the correct size.
   export CC="gcc -m32"
   export CXX="g++ -m32"
   export LD="gcc -m32"
-  LogExecute \
-    ${SRC_DIR}/configure --prefix=${NACL_HOST_PYROOT}
+  LogExecute ${SRC_DIR}/configure --prefix=${NACL_HOST_PYROOT}
 }
 
 InstallStep() {
   make install
 }