Using pip --user in test.sh script breaks ppc64le builds (#13388)

Summary:
Recent PR #13366 added --user to pip install breaks ppc64le testing when using test.sh. This fix makes it not be used for ppc64le builds/test as both ninja and hypothesis are already in ppc64le docker images.
Pull Request resolved: pytorch/pytorch#13388

Differential Revision: D12870164

Pulled By: soumith

fbshipit-source-id: b66bafc06ad2c5116bb5ef5e4681cf9c776084aa

.jenkins/pytorch/test.sh

@@ -25,11 +25,14 @@ if [ -n "${IN_CIRCLECI}" ]; then
   fi
 fi
 
-# JIT C++ extensions require ninja.
-pip install -q ninja --user
+# --user breaks ppc64le builds and these packages are already in ppc64le docker
+if [[ "$BUILD_ENVIRONMENT" != *ppc64le* ]]; then
+  # JIT C++ extensions require ninja.
+  pip install -q ninja --user
 
-# TODO: move this to Docker
-pip install -q hypothesis --user
+  # TODO: move this to Docker
+  pip install -q hypothesis --user
+fi
 
 # DANGER WILL ROBINSON.  The LD_PRELOAD here could cause you problems
 # if you're not careful.  Check this if you made some changes and the