Add help to hir_analysis_unrecognized_intrinsic_function

To help remind forgetful people like me what step they forgot.

compiler/rustc_hir_analysis/messages.ftl

@@ -462,6 +462,7 @@ hir_analysis_unrecognized_atomic_operation =
 hir_analysis_unrecognized_intrinsic_function =
     unrecognized intrinsic function: `{$name}`
     .label = unrecognized intrinsic
+    .help = if you're adding an intrinsic, be sure to update `check_intrinsic_type`
 
 hir_analysis_unused_associated_type_bounds =
     unnecessary associated type bound for not object safe associated type

compiler/rustc_hir_analysis/src/errors.rs

@@ -143,6 +143,7 @@ pub struct WrongNumberOfGenericArgumentsToIntrinsic<'a> {
 
 #[derive(Diagnostic)]
 #[diag(hir_analysis_unrecognized_intrinsic_function, code = E0093)]
+#[help]
 pub struct UnrecognizedIntrinsicFunction {
     #[primary_span]
     #[label]

tests/ui/error-codes/E0093.stderr

@@ -3,6 +3,8 @@ error[E0093]: unrecognized intrinsic function: `foo`
    |
 LL |     fn foo();
    |     ^^^^^^^^^ unrecognized intrinsic
+   |
+   = help: if you're adding an intrinsic, be sure to update `check_intrinsic_type`
 
 error: aborting due to 1 previous error
 

tests/ui/feature-gates/feature-gate-abi.stderr

@@ -187,12 +187,16 @@ error[E0093]: unrecognized intrinsic function: `f1`
    |
 LL | extern "rust-intrinsic" fn f1() {}
    |                            ^^ unrecognized intrinsic
+   |
+   = help: if you're adding an intrinsic, be sure to update `check_intrinsic_type`
 
 error[E0093]: unrecognized intrinsic function: `f2`
   --> $DIR/feature-gate-abi.rs:18:32
    |
 LL | extern "platform-intrinsic" fn f2() {}
    |                                ^^ unrecognized intrinsic
+   |
+   = help: if you're adding an intrinsic, be sure to update `check_intrinsic_type`
 
 error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
   --> $DIR/feature-gate-abi.rs:25:32

tests/ui/feature-gates/feature-gate-intrinsics.stderr

@@ -21,12 +21,16 @@ error[E0093]: unrecognized intrinsic function: `bar`
    |
 LL |     fn bar();
    |     ^^^^^^^^^ unrecognized intrinsic
+   |
+   = help: if you're adding an intrinsic, be sure to update `check_intrinsic_type`
 
 error[E0093]: unrecognized intrinsic function: `baz`
   --> $DIR/feature-gate-intrinsics.rs:5:28
    |
 LL | extern "rust-intrinsic" fn baz() {}
    |                            ^^^ unrecognized intrinsic
+   |
+   = help: if you're adding an intrinsic, be sure to update `check_intrinsic_type`
 
 error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
   --> $DIR/feature-gate-intrinsics.rs:5:34

tests/ui/intrinsics-always-extern.stderr

@@ -9,6 +9,8 @@ error[E0093]: unrecognized intrinsic function: `hello`
    |
 LL | extern "rust-intrinsic" fn hello() {
    |                            ^^^^^ unrecognized intrinsic
+   |
+   = help: if you're adding an intrinsic, be sure to update `check_intrinsic_type`
 
 error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
   --> $DIR/intrinsics-always-extern.rs:8:43