Add back `const` keyword to keep consumers forward compatible by
reverting https://github.com/hunspell/hunspell/commit/dd4b14899bfb

--- src/hunspell/hunspell.cxx.orig	2016-11-28 10:34:55 UTC
+++ src/hunspell/hunspell.cxx
@@ -110,7 +110,7 @@ public:
   int remove(const std::string& word);
   const std::string& get_version() const;
   struct cs_info* get_csconv();
-  std::vector<char> dic_encoding_vec;
+
 
 private:
   AffixMgr* pAMgr;
@@ -181,9 +181,6 @@ HunspellImpl::HunspellImpl(const char* a
   complexprefixes = pAMgr->get_complexprefixes();
   wordbreak = pAMgr->get_breaktable();
 
-  dic_encoding_vec.resize(encoding.size()+1);
-  strcpy(&dic_encoding_vec[0], encoding.c_str());
-
   /* and finally set up the suggestion manager */
   pSMgr = new SuggestMgr(try_string, MAXSUGGESTION, pAMgr);
   if (try_string)
@@ -1850,8 +1847,8 @@ int Hunspell::suffix_suggest(char*** sls
   return munge_vector(slst, stems);
 }
 
-char* Hunspell::get_dic_encoding() {
-  return &(m_Impl->dic_encoding_vec[0]);
+const char* Hunspell::get_dic_encoding() const {
+  return Hunspell_get_dic_encoding((Hunhandle*)(this));
 }
 
 int Hunspell::stem(char*** slst, char** desc, int n) {
@@ -1896,8 +1893,8 @@ int Hunspell_spell(Hunhandle* pHunspell,
   return reinterpret_cast<Hunspell*>(pHunspell)->spell(std::string(word));
 }
 
-char* Hunspell_get_dic_encoding(Hunhandle* pHunspell) {
-  return reinterpret_cast<Hunspell*>(pHunspell)->get_dic_encoding();
+const char* Hunspell_get_dic_encoding(Hunhandle* pHunspell) {
+  return (reinterpret_cast<Hunspell*>(pHunspell)->get_dict_encoding()).c_str();
 }
 
 int Hunspell_suggest(Hunhandle* pHunspell, char*** slst, const char* word) {
--- src/hunspell/hunspell.h.orig	2016-11-28 10:34:55 UTC
+++ src/hunspell/hunspell.h
@@ -68,7 +68,7 @@ LIBHUNSPELL_DLL_EXPORTED int Hunspell_ad
  */
 LIBHUNSPELL_DLL_EXPORTED int Hunspell_spell(Hunhandle* pHunspell, const char*);
 
-LIBHUNSPELL_DLL_EXPORTED char* Hunspell_get_dic_encoding(Hunhandle* pHunspell);
+LIBHUNSPELL_DLL_EXPORTED const char* Hunspell_get_dic_encoding(Hunhandle* pHunspell);
 
 /* suggest(suggestions, word) - search suggestions
  * input: pointer to an array of strings pointer and the (bad) word
--- src/hunspell/hunspell.hxx.orig	2016-11-28 10:34:55 UTC
+++ src/hunspell/hunspell.hxx
@@ -155,7 +155,7 @@ class LIBHUNSPELL_DLL_EXPORTED Hunspell 
   H_DEPRECATED void free_list(char*** slst, int n);
 
   const std::string& get_dict_encoding() const;
-  char* get_dic_encoding();
+  H_DEPRECATED const char* get_dic_encoding() const;
 
   /* morphological functions */