[lldb/SWIG] Refactor extensions to be non Python-specific

The current SWIG extensions for the string conversion operator is Python
specific because it uses the PythonObjects. This means that the code
cannot be reused for other SWIG supported languages such as Lua.

This reimplements the extensions in a more generic way that can be
reused.

Differential revision: https://reviews.llvm.org/D72377

Author: JDevlieghere

lldb/scripts/Python/python-extensions.swig

@@ -1,4 +1,3 @@
-
 %extend lldb::SBAddress {
         %nothreadallow;
         PyObject *lldb::SBAddress::__str__ (){
@@ -502,18 +501,6 @@
 }
 
 %extend lldb::SBTarget {
-        %nothreadallow;
-        PyObject *lldb::SBTarget::__str__ (){
-                lldb::SBStream description;
-                $self->GetDescription (description, lldb::eDescriptionLevelBrief);
-                const char *desc = description.GetData();
-                size_t desc_len = description.GetSize();
-                if (desc_len > 0 && (desc[desc_len-1] == '\n' || desc[desc_len-1] == '\r'))
-                    --desc_len;
-                return PythonString(llvm::StringRef(desc, desc_len)).release();
-        }
-        %clearnothreadallow;
-
     %pythoncode %{
         def __eq__(self, rhs):
             if not isinstance(rhs, type(self)):

lldb/scripts/interface/SBTarget.i

@@ -8,7 +8,6 @@
 
 namespace lldb {
 
-
 %feature("docstring",
 "Represents the target program running under the debugger.
 
@@ -968,6 +967,22 @@ public:
     lldb::SBValue
     EvaluateExpression (const char *expr, const lldb::SBExpressionOptions &options);
 
+  %extend {
+    %nothreadallow;
+    std::string lldb::SBTarget::__str__(){
+      lldb::SBStream stream;
+      $self->GetDescription (stream, lldb::eDescriptionLevelBrief);
+
+      const char *desc = stream.GetData();
+      size_t desc_len = stream.GetSize();
+      if (desc_len > 0 && (desc[desc_len-1] == '\n' || desc[desc_len-1] == '\r'))
+        --desc_len;
+
+      return std::string(desc, desc_len);
+    }
+    %clearnothreadallow;
+  }
+
 #ifdef SWIGPYTHON
     %pythoncode %{
         class modules_access(object):

lldb/scripts/lldb.swig

@@ -93,6 +93,7 @@ def lldb_iter(obj, getsize, getelem):
         yield elem(i)
 %}
 
+%include <std_string.i>
 %include "./Python/python-typemaps.swig"
 %include "./headers.swig"
 

lldb/scripts/lldb_lua.swig

@@ -8,6 +8,7 @@
 
 %module lldb
 
+%include <std_string.i>
 %include "./headers.swig"
 
 %{