ci: when installing rust-toolchain-installer-master, install it in debug mode to save some time in ci.

the compiletime optimizations probably take longer than the speedup we get when executing the optimized binary vs debug build.

.travis.yml

@@ -76,7 +76,7 @@ matrix:
 script:
   - |
       rm rust-toolchain
-      cargo install rustup-toolchain-install-master || echo "rustup-toolchain-install-master already installed"
+      cargo install rustup-toolchain-install-master --debug || echo "rustup-toolchain-install-master already installed"
       RUSTC_HASH=$(git ls-remote https://github.com/rust-lang/rust.git master | awk '{print $1}')
       travis_retry rustup-toolchain-install-master -f -n master $RUSTC_HASH
       rustup default master

appveyor.yml

@@ -21,7 +21,7 @@ install:
     - git ls-remote https://github.com/rust-lang/rust.git master | awk '{print $1}' >rustc-hash.txt
     - set /p RUSTC_HASH=<rustc-hash.txt
     - del rust-toolchain
-    - cargo install rustup-toolchain-install-master || echo "rustup-toolchain-install-master already installed"
+    - cargo install rustup-toolchain-install-master --debug || echo "rustup-toolchain-install-master already installed"
     - rustup-toolchain-install-master %RUSTC_HASH% -f -n master
     - rustup default master
     - set PATH=%PATH%;C:\Users\appveyor\.rustup\toolchains\master\bin