Don't force optional that is no longer there

Change-Id: I862649f615e20cf98369f7dcbff89594686ff7c5

ci/travis_script_python.sh

@@ -106,7 +106,7 @@ python_version_tests() {
   # Other stuff pip install
   pip install -r requirements.txt
 
-  python setup.py build_ext --inplace --with-parquet --with-jemalloc
+  python setup.py build_ext --inplace --with-parquet
 
   python -c "import pyarrow.parquet"
   python -c "import pyarrow._jemalloc"

site/README.md

@@ -73,11 +73,11 @@ rsync -r html/ ../../site/asf-site/docs/cpp
 
 #### Python
 
-First, build PyArrow with all optional extensions (Apache Parquet, jemalloc).
+First, build PyArrow with all optional extensions (Apache Parquet).
 
 ```
 cd ../python
-python setup.py build_ext --inplace --with-parquet --with-jemalloc
+python setup.py build_ext --inplace --with-parquet
 python setup.py build_sphinx -s doc/source
 rsync -r doc/_build/html/ ../site/asf-site/docs/python/
 ```