Move install_infra before execute build_wheels.sh

The pip_install_gr function in build_wheels.sh use requirements project.
So requirements project must exist before execute build_wheels.sh.
Then we moved install_infra function which install requirements project.

Change-Id: I8f80ecafff0f7e1942731379b70bccac338ea3b3
Closes-Bug: 1453012
diff --git a/stack.sh b/stack.sh
index e5ee0dc..f0aafaf 100755
--- a/stack.sh
+++ b/stack.sh
@@ -705,6 +705,9 @@
 # Virtual Environment
 # -------------------
 
+# Install required infra support libraries
+install_infra
+
 # Pre-build some problematic wheels
 if [[ -n ${WHEELHOUSE:-} && ! -d ${WHEELHOUSE:-} ]]; then
     source $TOP_DIR/tools/build_wheels.sh
@@ -713,10 +716,6 @@
 
 # Extras Pre-install
 # ------------------
-
-# Install required infra support libraries
-install_infra
-
 # Phase: pre-install
 run_phase stack pre-install