AddressSanitizer: alloc-dealloc-mismatch (malloc vs operator delete)

__cxa_demangle uses malloc/free for memory management, see
<http://itanium-cxx-abi.github.io/cxx-abi/abi.html#demangler>

Change-Id: I57f8465d1c70fbef4537068fd3aefc52295e1c63
Reviewed-on: https://gerrit.libreoffice.org/71942Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

tools/source/debug/debug.cxx

@@ -50,6 +50,7 @@
 #include <sal/log.hxx>
 #include <osl/thread.h>
 
+#include <cstdlib>
 #include <typeinfo>
 
 #include <tools/diagnose_ex.h>
@@ -116,7 +117,7 @@ OString exceptionToString(const css::uno::Any & caught)
         sMessage += " context: ";
         sMessage += pContext;
 #if defined __GLIBCXX__
-        delete pContext;
+        std::free(const_cast<char *>(pContext));
 #endif
     }
     {