Update try-build's expected output

Author: bjoernQ

tests-trybuild/tests/riscv-rt/core_interrupt/fail_signatures.stderr

@@ -1,16 +1,16 @@
-error: `#[core_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[core_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
  --> tests/riscv-rt/core_interrupt/fail_signatures.rs:2:1
   |
 2 | fn my_interrupt(code: usize) {}
   | ^^
 
-error: `#[core_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[core_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
  --> tests/riscv-rt/core_interrupt/fail_signatures.rs:5:1
   |
 5 | fn my_other_interrupt() -> usize {}
   | ^^
 
-error: `#[core_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[core_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
  --> tests/riscv-rt/core_interrupt/fail_signatures.rs:8:1
   |
 8 | async fn my_async_interrupt() {}

tests-trybuild/tests/riscv-rt/exception/fail_signatures.stderr

@@ -1,16 +1,16 @@
-error: `#[exception]` function must have signature `[unsafe] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
+error: `#[exception]` function must have signature `[unsafe] [extern "C"] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
  --> tests/riscv-rt/exception/fail_signatures.rs:2:1
   |
 2 | fn my_exception(code: usize) {}
   | ^^
 
-error: `#[exception]` function must have signature `[unsafe] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
+error: `#[exception]` function must have signature `[unsafe] [extern "C"] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
  --> tests/riscv-rt/exception/fail_signatures.rs:5:1
   |
 5 | fn my_other_exception(trap_frame: &riscv_rt::TrapFrame, code: usize) {}
   | ^^
 
-error: `#[exception]` function must have signature `[unsafe] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
+error: `#[exception]` function must have signature `[unsafe] [extern "C"] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
  --> tests/riscv-rt/exception/fail_signatures.rs:8:1
   |
 8 | async fn my_async_exception(trap_frame: &riscv_rt::TrapFrame, code: usize) {}

tests-trybuild/tests/riscv-rt/external_interrupt/fail_signatures.stderr

@@ -1,16 +1,16 @@
-error: `#[external_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[external_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
   --> tests/riscv-rt/external_interrupt/fail_signatures.rs:31:1
    |
 31 | fn my_interrupt() -> usize {}
    | ^^
 
-error: `#[external_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[external_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
   --> tests/riscv-rt/external_interrupt/fail_signatures.rs:34:1
    |
 34 | fn my_other_interrupt(code: usize) -> usize {}
    | ^^
 
-error: `#[external_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[external_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
   --> tests/riscv-rt/external_interrupt/fail_signatures.rs:37:1
    |
 37 | async fn my_async_interrupt(code: usize) -> usize {}