Make the wasm_c_abi future compat warning a hard error

This is the next step in getting rid of the broken C abi for
wasm32-unknown-unknown.

compiler/rustc_lint/messages.ftl

@@ -974,6 +974,3 @@ lint_use_let_underscore_ignore_suggestion = use `let _ = ...` to ignore the expr
 
 lint_variant_size_differences =
     enum variant is more than three times larger ({$largest} bytes) than the next largest
-
-lint_wasm_c_abi =
-    older versions of the `wasm-bindgen` crate will be incompatible with future versions of Rust; please update to `wasm-bindgen` v0.2.88

compiler/rustc_lint/src/early/diagnostics.rs

@@ -430,7 +430,6 @@ pub(super) fn decorate_lint(
         BuiltinLintDiag::UnusedCrateDependency { extern_crate, local_crate } => {
             lints::UnusedCrateDependency { extern_crate, local_crate }.decorate_lint(diag)
         }
-        BuiltinLintDiag::WasmCAbi => lints::WasmCAbi.decorate_lint(diag),
         BuiltinLintDiag::IllFormedAttributeInput { suggestions } => {
             lints::IllFormedAttributeInput {
                 num_suggestions: suggestions.len(),

compiler/rustc_lint/src/lints.rs

@@ -2561,10 +2561,6 @@ pub(crate) struct UnusedCrateDependency {
     pub local_crate: Symbol,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(lint_wasm_c_abi)]
-pub(crate) struct WasmCAbi;
-
 #[derive(LintDiagnostic)]
 #[diag(lint_ill_formed_attribute_input)]
 pub(crate) struct IllFormedAttributeInput {