Fix J9 JVM segfault in dropped trace method resolution

The dropped trace was incorrectly setting bci=0 and casting a string literal
to jmethodID, causing JVMTI calls like GetMethodDeclaringClass() to segfault
when processing the JFR constant pool during shutdown.

Fixed by setting bci=BCI_ERROR to properly route the dropped trace to native
method resolution (fillNativeMethodInfo) instead of Java method resolution
(fillJavaMethodInfo), avoiding JVMTI calls on invalid method IDs.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: jbachorik

ddprof-lib/src/main/cpp/callTraceStorage.cpp

@@ -7,6 +7,7 @@
 #include "callTraceStorage.h"
 #include "counters.h"
 #include "common.h"
+#include "vmEntry.h" // For BCI_ERROR constant
 #include <string.h>
 #include <atomic>
 
@@ -46,6 +47,7 @@ CallTraceStorage::~CallTraceStorage() {
 
 CallTrace* CallTraceStorage::getDroppedTrace() {
     // Static dropped trace object - created once and reused
+    static const char dropped_method_name[] = "<dropped due to contention>";
     static struct {
         CallTrace trace;
         ASGCT_CallFrame frame; // Additional frame storage beyond the [1] in CallTrace
@@ -55,8 +57,8 @@ CallTrace* CallTraceStorage::getDroppedTrace() {
             .num_frames = 1,
             .trace_id = DROPPED_TRACE_ID,
             .frames = {{
-                .bci = 0,
-                .method_id = (jmethodID)"<dropped due to contention>"
+                .bci = BCI_ERROR, // Mark as native frame with error string
+                .method_id = (jmethodID)dropped_method_name // String name for native frame
             }}
         },
         .frame = {} // Unused but needed for proper alignment