Run compile step under travis_wait

If there are no warnings, we may end up compiling more than 10
minutes without output, in which case the build times out. Use
travis_wait to avoid this.

.travis.yml

@@ -64,7 +64,7 @@ before_script:
     # Enable IPv6
     - sudo sh -c 'echo 0 > /proc/sys/net/ipv6/conf/all/disable_ipv6'
     # Compile PHP
-    - ./travis/compile.sh
+    - travis_wait ./travis/compile.sh
     # Setup Extensions
     - . ./travis/ext/mysql/setup.sh
     - . ./travis/ext/mysqli/setup.sh