Bug#913271: segfault - broken rust compiling

[jnqnfe at gmail.com]

Package: llvm-7
Version: 1:7.0.1~+rc2-1
Severity: grave

I've just updated my Sid install and found that building Rust crates
with Cargo now fails with a seg fault.

Initially I fired a bug report at cargo to kick things off, but I've
now discovered that it relates to the llvm-7 update, as switching llvm7
packages back to testing versions fixes the problem.