Auto merge of #3045 - RalfJung:tier1-ci, r=RalfJung

make sure we test all tier 1 targets

i686-pc-windows-gnu was missing (and i686-pc-windows-msvc was being tested twice, as host and foreign target).

Author: bors

ci.sh

@@ -107,7 +107,7 @@ case $HOST_TARGET in
     MIRI_TEST_TARGET=i686-unknown-linux-gnu run_tests
     MIRI_TEST_TARGET=aarch64-unknown-linux-gnu run_tests
     MIRI_TEST_TARGET=aarch64-apple-darwin run_tests
-    MIRI_TEST_TARGET=i686-pc-windows-msvc run_tests
+    MIRI_TEST_TARGET=i686-pc-windows-gnu run_tests
     MIRI_TEST_TARGET=x86_64-unknown-freebsd run_tests_minimal hello integer vec panic/panic concurrency/simple atomic data_race env/var
     MIRI_TEST_TARGET=aarch64-linux-android run_tests_minimal hello integer vec panic/panic
     MIRI_TEST_TARGET=wasm32-wasi run_tests_minimal no_std integer strings