add pip install timing

Change-Id: I368fec44858bd97fc6a314fb20eed2b10932cbb1

inc/python

@@ -80,6 +80,8 @@ function pip_install {
         return
     fi
 
+    time_start "pip_install"
+
     PIP_UPGRADE=$(trueorfalse False PIP_UPGRADE)
     if [[ "$PIP_UPGRADE" = "True" ]] ; then
         upgrade="--upgrade"
@@ -137,6 +139,8 @@ function pip_install {
             $cmd_pip $upgrade \
             -r $test_req
     fi
+
+    time_stop "pip_install"
 }
 
 # get version of a package from global requirements file