Add a link to the relevant issue for ARM PAC handling

bindings/java/samples/Sample_arm64.java

@@ -217,6 +217,8 @@ public class Sample_arm64 implements UnicornConst, Arm64Const {
         System.out.format(">>> X2 = 0x%x\n", uc.reg_read(UC_ARM64_REG_X2));
     }
 
+    /* Test PAC support in the emulator. Code adapted from
+    https://github.com/unicorn-engine/unicorn/issues/1789#issuecomment-1536320351 */
     public static void test_arm64_pac() {
         long x1 = 0x0000aaaabbbbccccL;
 

samples/sample_arm64.c

@@ -301,6 +301,9 @@ static void test_arm64_hook_mrs()
     }                       \
 } while(0)
 
+
+/* Test PAC support in the emulator. Code adapted from
+https://github.com/unicorn-engine/unicorn/issues/1789#issuecomment-1536320351 */
 static void test_arm64_pac(void)
 {
     uc_engine *uc;