Consolidate UnixSignals setting/getting in Process.

See http://reviews.llvm.org/D5108 for details.

This change does the following:

* eliminates the Process::GetUnixSignals() virtual method and replaces with a fixed getter.
* replaces the Process UnixSignals storage with a shared pointer.
* adds a Process constructor variant that can be passed the UnixSignalsSP. When the constructor without the UnixSignalsSP is specified, the Host's default UnixSignals is used.
* adds a host-specific version of GetUnixSignals() that is used when we need the host's appropriate UnixSignals variant.
* replaces GetUnixSignals() overrides in PlatformElfCore, ProcessGDBRemote, ProcessFreeBSD and ProcessLinux with code that appropriately sets the Process::UnixSignals for the process.

This change also enables some future patches that will enable llgs to be used for local Linux debugging.

llvm-svn: 216748
diff --git a/lldb/source/Host/freebsd/Host.cpp b/lldb/source/Host/freebsd/Host.cpp
index 8174015..dc092e8 100644
--- a/lldb/source/Host/freebsd/Host.cpp
+++ b/lldb/source/Host/freebsd/Host.cpp
@@ -39,8 +39,9 @@
 #include "lldb/Core/DataExtractor.h"
 #include "lldb/Utility/CleanUp.h"
 
-#include "llvm/Support/Host.h"
+#include "Plugins/Process/Utility/FreeBSDSignals.h"
 
+#include "llvm/Support/Host.h"
 
 extern "C" {
     extern char **environ;
@@ -401,3 +402,11 @@
    done:
    return buf_sp;
 }
+
+const UnixSignalsSP&
+Host::GetUnixSignals ()
+{
+    static const lldb_private::UnixSignalsSP s_unix_signals_sp (new FreeBSDSignals ());
+    return s_unix_signals_sp;
+}
+