kdc: annotate libkdc Windows function annotations

Annotate libkdc APIs with KDC_LIB_{CALL,FUNCTION} to ensure correct calling
convention and optimized DLL importing on Windows.

Ensure Windows and libtool export tables are consistent.

kdc/misc.c

@@ -122,7 +122,7 @@ synthesize_client(krb5_context context,
     return ret;
 }
 
-krb5_error_code
+KDC_LIB_FUNCTION krb5_error_code KDC_LIB_CALL
 _kdc_db_fetch(krb5_context context,
 	      krb5_kdc_configuration *config,
 	      krb5_const_principal principal,
@@ -245,7 +245,7 @@ out:
     return ret;
 }
 
-void
+KDC_LIB_FUNCTION void KDC_LIB_CALL
 _kdc_free_ent(krb5_context context, hdb_entry_ex *ent)
 {
     hdb_free_entry (context, ent);