[libc++abi] Fix build failure in abort_message.cpp when vasprintf isn't provided

GitOrigin-RevId: befd8f82fe2050a6406c45d330577f46969c7c7d
diff --git a/src/abort_message.cpp b/src/abort_message.cpp
index c5abbe2..ad44063 100644
--- a/src/abort_message.cpp
+++ b/src/abort_message.cpp
@@ -44,15 +44,21 @@
 
     // Format the arguments into an allocated buffer. We leak the buffer on
     // purpose, since we're about to abort() anyway.
+#if defined(_LIBCXXABI_USE_CRASHREPORTER_CLIENT)
     char* buffer;
     va_list list;
     va_start(list, format);
     vasprintf(&buffer, format, list);
     va_end(list);
 
-#if defined(_LIBCXXABI_USE_CRASHREPORTER_CLIENT)
     CRSetCrashLogMessage(buffer);
 #elif defined(__BIONIC__)
+    char* buffer;
+    va_list list;
+    va_start(list, format);
+    vasprintf(&buffer, format, list);
+    va_end(list);
+
 #   if __ANDROID_API__ >= 21
     // Show error in tombstone.
     android_set_abort_message(buffer);