Misc module/dwarf logging improvements

This change improves the logging for the lldb.module category to note a few interesting cases:

1. Local object file found, but specs not matching
2. Local object file not found, using a placeholder module

The handling and logging for the cases wehre we fail to load compressed dwarf
symbols is also improved.

Differential Revision: https://reviews.llvm.org/D50274

llvm-svn: 339161
diff --git a/lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp b/lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp
index 86ee212..95229b9 100644
--- a/lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp
+++ b/lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp
@@ -365,6 +365,12 @@
       // This enables most LLDB functionality involving address-to-module
       // translations (ex. identifing the module for a stack frame PC) and
       // modules/sections commands (ex. target modules list, ...)
+      if (log) {
+        log->Printf("Unable to locate the matching object file, creating a "
+                    "placeholder module for: %s",
+                    name.getValue().c_str());
+      }
+
       auto placeholder_module =
           std::make_shared<PlaceholderModule>(module_spec);
       placeholder_module->CreateImageSection(module, GetTarget());