Make this build on NetBSD.

[yyamano]

No description provided.

[matsumotory]

oh, already failed.

[yyamano]

I took a look the changes and the travis log, but I have no idea what is wrong. Will try it on Linux later.

[matsumotory]

fm... it's strange than the following error occurred:

curl: /usr/local/lib/libssl.so.1.0.0: no version information available (required by /usr/lib/x86_64-linux-gnu/libcurl.so.4)
curl: /usr/local/lib/libssl.so.1.0.0: no version information available (required by /usr/lib/x86_64-linux-gnu/libcurl.so.4)
curl: /usr/local/lib/libcrypto.so.1.0.0: no version information available (required by /usr/lib/x86_64-linux-gnu/libcurl.so.4)

[yyamano]

I can't reproduce it on CentOS 7.2.

curl: /usr/local/lib/libssl.so.1.0.0: no version information available (required by /usr/lib/x86_64-linux-gnu/libcurl.so.4)

You can see same messages on successful build. (e.g. https://travis-ci.org/matsumoto-r/ngx_mruby/jobs/149922866)

[yyamano]

I compared travis log between the last successful build and the failed one.

Travis build system seems to be upgraded. Not sure if it breaks build.

-Description:   Ubuntu 14.04.3 LTS
+Description:   Ubuntu 14.04.4 LTS

-gcc (Ubuntu 4.8.4-2ubuntu1~14.04) 4.8.4
[snip]
+gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4

[yyamano]

Hmm, I can't reproduce it on Ubuntu 14.04.5.

[matsumotory]

I confirm the PR pass the test locally. So, I merged now. Thanks!