[lldb] Attempt to fix signal-in-leaf-function-aarch64 on darwin

Convert settings set EXC_BAD_INSTRUCTION to SIGILL so we get uniform
behavior (and can resume the inferior).

Fix a "omitting the parameter name in a function definition is a C23
extension" warning as a drive-by.

Author: labath

lldb/test/Shell/Unwind/Inputs/signal-in-leaf-function-aarch64.c

@@ -7,7 +7,7 @@ int __attribute__((naked)) signal_generating_add(int a, int b) {
       "ret");
 }
 
-void sigill_handler(int) { _exit(0); }
+void sigill_handler(int signo) { _exit(0); }
 
 int main() {
   signal(SIGILL, sigill_handler);

lldb/test/Shell/Unwind/signal-in-leaf-function-aarch64.test

@@ -4,6 +4,9 @@
 # RUN: %clang_host %S/Inputs/signal-in-leaf-function-aarch64.c -o %t
 # RUN: %lldb -s %s -o exit %t | FileCheck %s
 
+# Convert EXC_BAD_INSTRUCTION to SIGILL on darwin
+settings set platform.plugin.darwin.ignored-exceptions EXC_BAD_INSTRUCTION
+
 breakpoint set -n sigill_handler
 # CHECK: Breakpoint 1: where = {{.*}}`sigill_handler