Makefile: Build Rust code on Ubuntu Trusty

My production server is on Ubuntu 14.04, but I was building the FastCGI
executables with Debian Stretch.

Discovered the problem like this:

    $ ./fulfillment.fcgi
    ./fulfillment.fcgi: error while loading shared libraries: libssl.so.1.1: cannot open shared object file: No such file or directory
    $ ldd fulfillment.fcgi
            linux-vdso.so.1 =>  (0x000003a94301e000)
            libssl.so.1.1 => not found
            libcrypto.so.1.1 => not found
            libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x000003a94273d000)
            librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x000003a942535000)
            libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x000003a942317000)
            libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x000003a942101000)
            libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x000003a941d38000)
            /lib64/ld-linux-x86-64.so.2 (0x000003a942dfe000)
            libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x000003a941a32000)

In order to link against the right dynamic libraries, build on Ubuntu
Trusty. To do that, I downloaded the Dockerfile at:
https://github.com/rust-lang-nursery/docker-rust/blob/c34d6993e8f9403c18f348de85787f1585fd3375/1.30.1/stretch/Dockerfile

and changed the first line to:

    FROM buildpack-deps:trusty

I then built an image from the Dockerfile and tagged it:

    $ docker image build .
    $ docker image tag IMAGE_ID rust:1.30.1-trusty

1 files changed, 1 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 5935744..a93270d 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,7 @@ license-generator/target/release/license:
 		--tty \
 		--volume $$PWD/license-generator:/app \
 		--workdir /app \
-		rust:1.30.1-stretch \
+		rust:1.30.1-trusty \
 		cargo build --release
 
 .PHONY: deploy