Add string abstraction to goto-analyzer and goto-diff

At the moment this code is dead and is only added to make the
process_goto_program steps more similar.  I will leave it to others
to decide if this is a useful thing to have and add the required command
line options and tests.  Should not affect the behaviour of either tool.

Author: martin

src/goto-analyzer/goto_analyzer_parse_options.cpp

@@ -42,6 +42,8 @@ Author: Daniel Kroening, [email protected]
 #include <goto-programs/set_properties.h>
 #include <goto-programs/show_properties.h>
 #include <goto-programs/show_symbol_table.h>
+#include <goto-programs/string_abstraction.h>
+#include <goto-programs/string_instrumentation.h>
 #include <goto-programs/validate_goto_model.h>
 
 #include <analyses/call_stack_history.h>
@@ -884,6 +886,9 @@ bool goto_analyzer_parse_optionst::process_goto_program(
 
     add_malloc_may_fail_variable_initializations(goto_model);
 
+    if(options.get_bool_option("string-abstraction"))
+      string_instrumentation(goto_model);
+
     // remove function pointers
     log.status() << "Removing function pointers and virtual functions"
                  << messaget::eom;

src/goto-diff/goto_diff_parse_options.cpp

@@ -333,6 +333,9 @@ bool goto_diff_parse_optionst::process_goto_program(
 
     add_malloc_may_fail_variable_initializations(goto_model);
 
+    if(options.get_bool_option("string-abstraction"))
+      string_instrumentation(goto_model);
+
     // remove function pointers
     log.status() << "Removal of function pointers and virtual functions"
                  << messaget::eom;