Set test = false in the compiletest binary crate

The binary crate is a tiny stub; all of the logic and tests should be in the
library crate.

Disabling unit tests for the binary crate makes `x test compiletest` less
noisy.

Author: Zalathar

src/tools/compiletest/Cargo.toml

@@ -9,6 +9,9 @@ doctest = false
 [[bin]]
 name = "compiletest"
 path = "src/bin/main.rs"
+# The compiletest binary crate is a tiny stub that shouldn't contain any unit
+# tests of its own; all of the logic is in the library crate.
+test = false
 
 [dependencies]
 # tidy-alphabetical-start