[travis] fix typo

.travis.yml

@@ -170,6 +170,7 @@ before_install:
           if [[ $PHP = hhvm* ]]; then
               continue
           fi
+          export PHP=$PHP
           phpenv global $PHP
           INI=~/.phpenv/versions/$PHP/etc/conf.d/travis.ini
           if [[ $PHP = 5.* ]]; then
@@ -267,7 +268,7 @@ install:
     - |
       run_tests () {
           set -e
-          PHP=$1
+          export PHP=$1
           if [[ $PHP != $TRAVIS_PHP_VERSION && $TRAVIS_PULL_REQUEST != false ]]; then
               echo -e "\\n\\e[33;1mIntermediate PHP version $PHP is skipped for pull requests.\\e[0m"
               return
@@ -297,6 +298,7 @@ install:
               echo "$COMPONENTS" | parallel --gnu "tfold {} $PHPUNIT_X {}"
               tfold src/Symfony/Component/Console.tty $PHPUNIT src/Symfony/Component/Console --group tty
               if [[ $PHP = ${MIN_PHP%.*} ]]; then
+                  export PHP=$MIN_PHP
                   echo -e "1\\n0" | xargs -I{} bash -c "tfold src/Symfony/Component/Process.sigchild{} SYMFONY_DEPRECATIONS_HELPER=weak ENHANCE_SIGCHLD={} php-$MIN_PHP/sapi/cli/php .phpunit/phpunit-4.8-1/phpunit --colors=always src/Symfony/Component/Process/"
               fi
           fi