fix compatiblity with heimdal :
* fix bashism '=='
* test libkrb5 instead of krb5-private.h for _krb5_principal2principalname
* include <gssapi/gssapi_krb5.h> even if HAVE_HEIMDAL_KERBEROS for krb5_gss_register_acceptor_identity
* initialize PrincipalName *pn
--- a/configure
+++ b/configure
@@ -2963,7 +2963,7 @@
 		fi
 		ac_krb5_solaris="`$krb5confpath --version 2>/dev/null | grep -i solaris`"
 		ac_krb5_heimdal="`$krb5confpath --version 2>/dev/null | grep -i heimdal`"
-        	if test "x$ac_krb5_solaris" == x ; then
+        	if test "x$ac_krb5_solaris" = x ; then
 			ac_krb5_cflags=`$krb5confpath --cflags krb5 2> /dev/null `
 			if test $? != 0; then
 				krb5fail=t
@@ -3455,29 +3455,6 @@
 
 done
 
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for _krb5_principal2principalname in krb5-private.h" >&5
-$as_echo_n "checking for _krb5_principal2principalname in krb5-private.h... " >&6; }
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <krb5-private.h>
-
-_ACEOF
-if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  $EGREP "_krb5_principal2principalname" >/dev/null 2>&1; then :
-
-$as_echo "#define HAVE_KRB5_PRINCIPAL2PRINCIPAL 1" >>confdefs.h
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-rm -f conftest*
-
-
-ac_com_error_message=no
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <krb5.h>
@@ -4118,6 +4095,57 @@
 fi
 
 fi
+if test "x$ac_krb5_heimdal" != x ; then
+	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for _krb5_principal2principalname in -lkrb5" >&5
+printf %s "checking for _krb5_principal2principalname in -lkrb5... " >&6; }
+if test ${ac_cv_lib_krb5__krb5_principal2principalname+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) ac_check_lib_save_LIBS=$LIBS
+LIBS="-lkrb5  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.
+   The 'extern "C"' is for builds by C++ compilers;
+   although this is not generally supported in C code supporting it here
+   has little cost and some practical benefit (sr 110532).  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char _krb5_principal2principalname (void);
+int
+main (void)
+{
+return _krb5_principal2principalname ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_lib_krb5__krb5_principal2principalname=yes
+else case e in #(
+  e) ac_cv_lib_krb5__krb5_principal2principalname=no ;;
+esac
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_krb5__krb5_principal2principalname" >&5
+printf "%s\n" "$ac_cv_lib_krb5__krb5_principal2principalname" >&6; }
+if test "x$ac_cv_lib_krb5__krb5_principal2principalname" = xyes
+then :
+
+printf "%s\n" "#define HAVE_KRB5_PRINCIPAL2PRINCIPAL 1" >>confdefs.h
+
+fi
+fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for krb5_get_err_text in -lkrb5" >&5
 $as_echo_n "checking for krb5_get_err_text in -lkrb5... " >&6; }
 if ${ac_cv_lib_krb5_krb5_get_err_text+:} false; then :
--- a/mod_gss.h.in
+++ b/mod_gss.h.in
@@ -204,7 +204,6 @@
 #include <gssapi/gssapi.h>
 #endif /* HAVE_GSSAPI_H */
 
-#ifndef HAVE_HEIMDAL_KERBEROS
 #ifdef HAVE_GSSAPI_GSSAPI_EXT_H
 #include <gssapi/gssapi_ext.h>
 #endif /* HAVE_GSSAPI_GSSAPI_EXT_H */
@@ -214,7 +213,6 @@
 #ifdef HAVE_GSSAPI_GSSAPI_GENERIC_H
 #include <gssapi/gssapi_generic.h>
 #endif /* HAVE_GSSAPI_GSSAPI_GENERIC_H */
-#endif /* HAVE_HEIMDAL_KERBEROS */
 
 #ifndef HAVE_GSS_INT32
 #define gss_int32 int32_t
--- a/mod_auth_gss.c.in
+++ b/mod_auth_gss.c.in
@@ -109,7 +109,7 @@
     krb5_principal p;
     krb5_error_code kerr;
 #ifdef HAVE_HEIMDAL_KERBEROS
-    PrincipalName *pn;
+    PrincipalName *pn = NULL;
 #endif
     char *princ_name;
 
@@ -179,7 +179,7 @@
     krb5_principal p;
     krb5_error_code kerr;
 #ifdef HAVE_HEIMDAL_KERBEROS
-    PrincipalName *pn;
+    PrincipalName *pn = NULL;
 #endif
     char *princ_name;
 
@@ -251,7 +251,7 @@
     krb5_principal p;
     krb5_error_code kerr;
 #ifdef HAVE_HEIMDAL_KERBEROS
-    PrincipalName *pn;
+    PrincipalName *pn = NULL;
 #endif
     char *princ_name;