Update PHP tests to send warnings/errors to stderr

test/tests/php-ext-install/container.sh

@@ -2,10 +2,10 @@
 set -e
 
 docker-php-ext-install pdo_mysql 2>&1
-php -r 'exit(extension_loaded("pdo_mysql") ? 0 : 1);'
+php -d display_errors=stderr -r 'exit(extension_loaded("pdo_mysql") ? 0 : 1);'
 grep -q '^extension=' /usr/local/etc/php/conf.d/*pdo_mysql*.ini
 
 # opcache is pre-built by default at least as far back as PHP 5.5
 docker-php-ext-enable opcache 2>&1
-php -r 'exit(extension_loaded("Zend OPcache") ? 0 : 1);'
+php -d display_errors=stderr -r 'exit(extension_loaded("Zend OPcache") ? 0 : 1);'
 grep -q '^zend_extension=' /usr/local/etc/php/conf.d/*opcache*.ini

test/tests/run-php-in-container.sh

@@ -4,4 +4,4 @@ set -e
 testDir="$(readlink -f "$(dirname "$BASH_SOURCE")")"
 runDir="$(dirname "$(readlink -f "$BASH_SOURCE")")"
 
-source "$runDir/run-in-container.sh" "$testDir" "$1" php ./container.php
+source "$runDir/run-in-container.sh" "$testDir" "$1" php -d display_errors=stderr ./container.php