feat(samples): Make Native Crash button fault inside app native code (#5773)

The Native Crash button called raise(SIGSEGV), which faults inside libc and, for a JNI-originated crash, does not exercise symbolication of the app's own native code. Point it at a null-deref inside a named function (trigger_null_deref) instead, so the crashing frame resolves to a real symbol + source line and native symbolication can be verified from the sample.

Ref JAVA-645


Claude-Session: https://claude.ai/code/session_01EmE8hdaj9H9K61opK2PZ6U

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: runningcode

sentry-samples/sentry-samples-android/src/main/cpp/native-sample.cpp

@@ -1,15 +1,23 @@
 #include <jni.h>
 #include <android/log.h>
 #include <sentry.h>
-#include <signal.h>
 
 #define TAG "sentry-sample"
 
 extern "C" {
 
+// Faults inside this named function so the crashing frame resolves to a real
+// symbol + source line. A bare raise(SIGSEGV) would instead fault in libc and,
+// for a JNI-originated crash, not exercise app-native symbolication.
+[[gnu::noinline]]
+static void trigger_null_deref() {
+    volatile int *ptr = nullptr;
+    *ptr = 42;
+}
+
 JNIEXPORT void JNICALL Java_io_sentry_samples_android_NativeSample_crash(JNIEnv *env, jclass cls) {
     __android_log_print(ANDROID_LOG_WARN, TAG, "About to crash.");
-    raise(SIGSEGV);
+    trigger_null_deref();
 }
 
 JNIEXPORT void JNICALL Java_io_sentry_samples_android_NativeSample_message(JNIEnv *env, jclass cls) {