Use delete[] to de-allocate pointers from new[]

Upstream clang has a new diagnostic, '-Wmismatched-new-delete' to
generate a warning (that becomes an error with -Werror) when delete is
used to deallocate pointers created with 'new[]'.  This patch fixes
'delete's that trigger this warning/error.

Change-Id: I7551e856b4b13bfae4cb78b5664d8652322683cf
diff --git a/libbacktrace/backtrace_test.cpp b/libbacktrace/backtrace_test.cpp
index 760f5cc..6bd7529 100644
--- a/libbacktrace/backtrace_test.cpp
+++ b/libbacktrace/backtrace_test.cpp
@@ -974,8 +974,8 @@
           << "Offset at " << i << " length " << j << " wrote too much data";
     }
   }
-  delete data;
-  delete expected;
+  delete[] data;
+  delete[] expected;
 }
 
 TEST(libbacktrace, thread_read) {