Add new flag to allow granular control over the use of objdump.

This adds a new flag `enable_objdump_for_exploitability_` to the
MinidumpProcessor, which allows enabling objdump separately for crash
address fixups and for exploitability analysis, as the performance cost
of the exploitability analysis is significantly higher.

Change-Id: I667ffdce7cc0a970793f91413c3d2e3af93f4247
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/4507067
Reviewed-by: Ivan Penkov <ivanpe@google.com>
Reviewed-by: Ivan Penkov <ivanpe@chromium.org>

src/processor/minidump_processor.cc

@@ -375,9 +375,8 @@ ProcessResult MinidumpProcessor::Process(
   // rating.
   if (enable_exploitability_) {
     scoped_ptr<Exploitability> exploitability(
-        Exploitability::ExploitabilityForPlatform(dump,
-                                                  process_state,
-                                                  enable_objdump_));
+        Exploitability::ExploitabilityForPlatform(
+          dump, process_state, enable_objdump_for_exploitability_));
     // The engine will be null if the platform is not supported
     if (exploitability != NULL) {
       process_state->exploitability_ = exploitability->CheckExploitability();