Change uses of "spire" to "slang" (#461)

Fixes #350

When the Slang project forked off from the Spire research effort, we renamed things as we went, but many cases seem to have slipped through the cracks.

The two biggest diffs here are:

- The `hello` example program was incorrectly talking about what was in the shader file (Slang no longer supports the "module" or "pipeline" constructs from Spire), and so it wasn't just a simple rename.

- The files under `tests/bindings` were mistakenly using `__SPIRE__` as a preprocessor guard, which means that they weren't actually testing what they meant to. Luckily, it looks like the relevant functionality didn't regress while these tests were unintentionally deactivated.

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/bindings/README.md b/tests/bindings/README.md
index ccc9fecb9..c50edcf8d 100644
--- a/tests/bindings/README.md
+++ b/tests/bindings/README.md
@@ -21,9 +21,9 @@ The resulting code guarantees that `tb` will always be assigned to the same loca
 Methodology
 -----------
 
-These tests currently rely on the ability to run the same HLSL code through the Spire compiler driver and execute either Spire, or HLSL. We write an example like the above by wrapping explicit `register` semantics in a macro:
+These tests currently rely on the ability to run the same HLSL code through the Slang compiler driver and execute either Slang, or HLSL. We write an example like the above by wrapping explicit `register` semantics in a macro:
 
     Texture2D ta R(: register(t0));
     Texture2D tb R(: register(t1));
 
-In the HLSL case, these annotations will manually place things where we want them, while in the Spire case, we define the macro to have an empty expansion, so that the annotations express our expectation for what the compiler will auto-generate.
\ No newline at end of file
+In the HLSL case, these annotations will manually place things where we want them, while in the Slang case, we define the macro to have an empty expansion, so that the annotations express our expectation for what the compiler will auto-generate.
\ No newline at end of file