Add conformance test for php c back (#4966)

* Add conformance test for php c back

php c extension has different result for conformance test for different
php version and architecture. Try to add conformance back for php 7.1 c extension first.

* Disable conformance test for c extension on 32-bit architecture
32-bit and 64-bit have different failing tests

* Fix typo
diff --git a/tests.sh b/tests.sh
index 73be5c1..5bb8ae3 100755
--- a/tests.sh
+++ b/tests.sh
@@ -507,18 +507,21 @@
   phpunit
   popd
   pushd conformance
-  # TODO(teboring): Add it back
-  # make test_php
+  make test_php
   popd
 }
 
 build_php7.1_c() {
+  ENABLE_CONFORMANCE_TEST=$1
   use_php 7.1
   wget https://phar.phpunit.de/phpunit-5.6.0.phar -O /usr/bin/phpunit
   cd php/tests && /bin/bash ./test.sh 7.1 && cd ../..
-  pushd conformance
-  # make test_php_c
-  popd
+  if [ "$ENABLE_CONFORMANCE_TEST" = "true" ]
+  then
+    pushd conformance
+    make test_php_c
+    popd
+  fi
 }
 
 build_php7.1_zts_c() {
@@ -538,7 +541,7 @@
   build_php5.5_c
   build_php5.6_c
   build_php7.0_c
-  build_php7.1_c
+  build_php7.1_c $1
   build_php5.5_zts_c
   build_php5.6_zts_c
   build_php7.0_zts_c
@@ -546,7 +549,7 @@
 }
 
 build_php_all() {
-  build_php_all_32
+  build_php_all_32 true
   build_php_compatibility
 }