Do not suggest using -Zmacro-backtrace for builtin macros

For macros that are implemented on the compiler, we do *not* mention the `-Zmacro-backtrace` flag. This includes `derive`s and standard macros.

Author: estebank

tests/ui/alloc-error/alloc-error-handler-bad-signature-1.stderr

@@ -18,7 +18,6 @@ LL | fn oom(
    |    ^^^
 LL |     info: &Layout,
    |     -------------
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0308]: mismatched types
   --> $DIR/alloc-error-handler-bad-signature-1.rs:10:1
@@ -35,7 +34,6 @@ LL | |  }
    |
    = note:   expected type `!`
            found unit type `()`
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors
 

tests/ui/alloc-error/alloc-error-handler-bad-signature-2.stderr

@@ -26,7 +26,6 @@ LL | fn oom(
    |    ^^^
 LL |     info: Layout,
    |     ------------
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0308]: mismatched types
   --> $DIR/alloc-error-handler-bad-signature-2.rs:10:1
@@ -43,7 +42,6 @@ LL | |  }
    |
    = note:   expected type `!`
            found unit type `()`
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors
 

tests/ui/alloc-error/alloc-error-handler-bad-signature-3.stderr

@@ -14,7 +14,6 @@ note: function defined here
    |
 LL | fn oom() -> ! {
    |    ^^^
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 1 previous error