use new dir for CI and docs

.travis.yml

@@ -37,9 +37,13 @@ script:
   cargo test --release --all-features &&
   cargo install --all-features --force --path .
 - |
-  # Get ourselves a MIR-full libstd
+  # Get ourselves a MIR-full libstd, and use it henceforth
   cargo miri setup &&
-  export MIRI_SYSROOT=~/.miri/HOST
+  if [ "$TRAVIS_OS_NAME" == osx ]; then
+    export MIRI_SYSROOT=~/Library/Caches/miri.miri.miri/HOST
+  else
+    export MIRI_SYSROOT=~/.cache/miri/HOST
+  fi
 - |
   # Test miri with full MIR
   cargo test --release --all-features

README.md

@@ -91,7 +91,7 @@ Miri builds and vice-versa.
 
 You may be running `cargo miri` with a different compiler version than the one
 used to build the custom libstd that Miri uses, and Miri failed to detect that.
-Try deleting `~/.miri`.
+Try deleting `~/.cache/miri`.
 
 ## Miri `-Z` flags
 

appveyor.yml

@@ -30,9 +30,9 @@ test_script:
     # Test plain miri
     - cargo build --release --all-features --all-targets
     - cargo test --release --all-features
-    # Get ourselves a MIR-full libstd
+    # Get ourselves a MIR-full libstd, and use it henceforth
     - cargo run --release --all-features --bin cargo-miri -- miri setup
-    - set MIRI_SYSROOT=%USERPROFILE%\.miri\HOST
+    - set MIRI_SYSROOT=%USERPROFILE%\AppData\Local\miri\miri\cache\HOST
     # Test miri with full MIR
     - cargo test --release --all-features