ci: start sccache early and throw away the S3 access key

This avoids accidentally leaking the key in the build log.

.appveyor.yml

@@ -341,6 +341,11 @@ before_build:
         foreach { "$env:DENO_BUILD_PATH\$($Matches[1])" }
       Set-FilesNeeded -Auto -Path $outputs -Reason "Build dependency graph"
 
+  # Start sccache, then throw away the S3 access key.
+  - ps: |-
+      sccache --start-server
+      $env:AWS_SECRET_ACCESS_KEY = $null
+
 build_script:
   # Build with Cargo first. Both builds produce a deno.exe in the same dir. We
   # want the final one (which gets tested and released) to be built by Ninja.
@@ -363,6 +368,9 @@ after_test:
   # Remove stale files and empty dirs from the build directory.
   - ps: Stop-TraceFilesNeeded
 
+  # Stop sccache and show stats.
+  - ps: sccache --stop-server
+
   # Verify that the build is fully up-to-date. Running ninja should be a no-op.
   # This catches erroneous file cleanup, and incorrectly set up build deps.
   - ps: |-

.travis.yml

@@ -55,6 +55,10 @@ install:
   rm -rf "$RUSTUP_HOME"toolchains/*/share
 before_script:
 - ./tools/setup.py
+# Start sccache, then throw away the S3 access key.
+- |-
+  sccache --start-server
+  unset AWS_SECRET_ACCESS_KEY
 script:
 - |-
   # Check lint and format.
@@ -84,6 +88,7 @@ script:
   ./tools/build.py -C target/release -j2
   DENO_BUILD_MODE=release ./tools/test.py
 
+- sccache --stop-server
 before_deploy:
 - gzip -c target/release/deno > target/release/deno_${TRAVIS_OS_NAME}_x64.gz
 deploy: