minor symfony#41609 Optimize travis file a bit (nicolas-grekas)

This PR was merged into the 4.4 branch.

Discussion
----------

Optimize travis file a bit

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

Commits
-------

fe51b80 Optimize travis file a bit

Author: nicolas-grekas

.travis.yml

@@ -120,7 +120,7 @@ before_install:
       # php.ini configuration
       (
           for PHP in $TRAVIS_PHP_VERSION $php_extra; do
-              (cd / && wget https://storage.googleapis.com/travis-ci-language-archives/php/binaries/ubuntu/18.04/x86_64/php-$PHP.tar.bz2 -O - | tar -xj) &
+              ([[ $PHP != 7.4 ]] && phpenv global $PHP 2>/dev/null) || (cd / && wget https://storage.googleapis.com/travis-ci-language-archives/php/binaries/ubuntu/18.04/x86_64/php-$PHP.tar.bz2 -O - | tar -xj) &
           done
           wait
       )