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

ports/python-host/build.sh

Index: ports/python-host/build.sh
diff --git a/ports/python_modules/python-host/build.sh b/ports/python-host/build.sh
similarity index 82%
rename from ports/python_modules/python-host/build.sh
rename to ports/python-host/build.sh
index a5a9e3a8092e3042086afa97df5677a900b3516c..773e71b7f8626a25b7e861699a2849db6713cd28 100644
--- a/ports/python_modules/python-host/build.sh
+++ b/ports/python-host/build.sh
@@ -5,11 +5,9 @@
 # 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
@@ -17,8 +15,7 @@ ConfigureStep() {
   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() {