[NFC] Turn "load dependent files" boolean into an enum

This is an NFC commit to refactor the "load dependent files" parameter
from a boolean to an enum value. We want to be able to specify a
default, in which case we decide whether or not to load the dependent
files based on whether the target is an executable or not (i.e. a
dylib).

This is a dependency for D51934.

Differential revision: https://reviews.llvm.org/D51859

llvm-svn: 342633
diff --git a/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp b/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp
index c9ec685..8a5f998 100644
--- a/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp
@@ -319,7 +319,7 @@
                   // Make sure you don't already have the right module loaded
                   // and they will be uniqued
                   if (exe_module_sp.get() != module_sp.get())
-                    target.SetExecutableModule(module_sp, false);
+                    target.SetExecutableModule(module_sp, eLoadDependentsNo);
                 }
               }
             }