Revert "Add --rust-target to replace --unstable-rust"

This reverts commit 0bb7b9f1c4652f63f41eba4064b79c044fd3d955.

It turns out our CI stopped running test expectations in an earlier
regression (from d73507e; fix incoming) and so this pull request actually
introduced a bunch of failures when compiling the test expectations and running
their unit tests :(

1 files changed, 0 insertions, 13 deletions

diff --git a/tests/headers/use-core_1_0.h b/tests/headers/use-core_1_0.h
deleted file mode 100644
index afa54d42..00000000
--- a/tests/headers/use-core_1_0.h
+++ /dev/null
@@ -1,13 +0,0 @@
-// bindgen-flags: --rust-target 1.0 --use-core --raw-line "extern crate core;"
-
-struct foo {
-  int a, b;
-  void* bar;
-};
-
-union {
-  int bar;
-  long baz;
-} bazz;
-
-typedef void (*fooFunction)(int bar);