Fix base_name of return' symbol to match its name

Author: chrisr-diffblue

regression/cbmc/typedef-return-anon-struct1/test.desc

@@ -5,7 +5,7 @@ main.c
 activate-multi-line-match
 EXIT=0
 SIGNAL=0
-Base name\.+: return\nMode\.+: C\nType\.+: MYSTRUCT
+Base name\.+: return'\nMode\.+: C\nType\.+: MYSTRUCT
 Base name\.+: fun\nMode\.+: C\nType\.+: MYSTRUCT \(\)
 --
 warning: ignoring

regression/goto-instrument-typedef/typedef-return-anon-struct1/test.desc

@@ -5,7 +5,7 @@ main.c
 activate-multi-line-match
 EXIT=0
 SIGNAL=0
-Base name\.+: return\nMode\.+: C\nType\.+: MYSTRUCT
+Base name\.+: return'\nMode\.+: C\nType\.+: MYSTRUCT
 Base name\.+: fun\nMode\.+: C\nType\.+: MYSTRUCT \(\)
 --
 warning: ignoring

src/ansi-c/ansi_c_entry_point.cpp

@@ -237,7 +237,7 @@ bool generate_ansi_c_start_function(
     return_symbol.mode=ID_C;
     return_symbol.is_static_lifetime=false;
     return_symbol.name="return'";
-    return_symbol.base_name="return";
+    return_symbol.base_name = "return'";
     return_symbol.type=to_code_type(symbol.type).return_type();
 
     symbol_table.add(return_symbol);