Add CI for s390x-unknown-linux-gnu (#392)

Author: uweigand

.github/workflows/main.yml

@@ -139,6 +139,7 @@ jobs:
         - i586-unknown-linux-gnu
         - i686-unknown-linux-gnu
         - powerpc64-unknown-linux-gnu
+        - s390x-unknown-linux-gnu
         - x86_64-pc-windows-gnu
         - x86_64-unknown-linux-gnu
         - x86_64-unknown-linux-musl

ci/docker/s390x-unknown-linux-gnu/Dockerfile

@@ -0,0 +1,17 @@
+FROM ubuntu:20.04
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc \
+    ca-certificates \
+    libc6-dev \
+    gcc-s390x-linux-gnu \
+    libc6-dev-s390x-cross \
+    qemu-user \
+    # There seems to be a bug in processing mixed-architecture
+    # ld.so.cache files that causes crashes in some cases.  Work
+    # around this by simply deleting the cache for now.
+    && rm /etc/ld.so.cache
+
+ENV CARGO_TARGET_S390X_UNKNOWN_LINUX_GNU_LINKER=s390x-linux-gnu-gcc \
+    CARGO_TARGET_S390X_UNKNOWN_LINUX_GNU_RUNNER="qemu-s390x -L /usr/s390x-linux-gnu" \
+    CC=s390x-linux-gnu-gcc

tests/concurrent-panics.rs

@@ -14,7 +14,12 @@ fn main() {
     // so just skip these for CI. No other reason this can't run on those
     // platforms though.
     // Miri does not have support for re-execing a file
-    if cfg!(unix) && (cfg!(target_arch = "arm") || cfg!(target_arch = "aarch64")) || cfg!(miri) {
+    if cfg!(unix)
+        && (cfg!(target_arch = "arm")
+            || cfg!(target_arch = "aarch64")
+            || cfg!(target_arch = "s390x"))
+        || cfg!(miri)
+    {
         println!("test result: ok");
         return;
     }