Roll back libc in the ci scripts too

ci/rustup.sh

@@ -4,9 +4,15 @@
 
 set -ex
 
-for toolchain in 1.8.0 1.15.0 beta nightly; do
-    run="rustup run $toolchain"
+export TRAVIS_RUST_VERSION
+for TRAVIS_RUST_VERSION in 1.8.0 1.15.0 beta nightly; do
+    run="rustup run $TRAVIS_RUST_VERSION"
+    if [ "$TRAVIS_RUST_VERSION" = 1.8.0 ]; then
+      # libc 0.2.34 started using #[deprecated]
+      $run cargo generate-lockfile
+      $run cargo update --package libc --precise 0.2.33 || :
+    fi
     $run cargo build --verbose
-    $run $PWD/ci/test_full.sh $toolchain
+    $run $PWD/ci/test_full.sh
     $run cargo doc
 done

ci/test_full.sh

@@ -2,10 +2,15 @@
 
 set -ex
 
-echo Testing num on rustc ${TRAVIS_RUST_VERSION:=$1}
+echo Testing num on rustc ${TRAVIS_RUST_VERSION}
 
 # All of these packages should build and test everywhere.
 for package in bigint complex integer iter rational traits; do
+  if [ "$TRAVIS_RUST_VERSION" = 1.8.0 ]; then
+    # libc 0.2.34 started using #[deprecated]
+    cargo generate-lockfile --manifest-path $package/Cargo.toml
+    cargo update --manifest-path $package/Cargo.toml --package libc --precise 0.2.33 || :
+  fi
   cargo build --manifest-path $package/Cargo.toml
   cargo test --manifest-path $package/Cargo.toml
 done