rename add_throws_exceptions

This is follow up for #4618, and a addresses a comment by Chris.  The method
only adds one exception, not multiple.

Author: Daniel Kroening

jbmc/src/java_bytecode/java_bytecode_convert_method.cpp

@@ -561,7 +561,7 @@ void java_bytecode_convert_methodt::convert(
   method_symbol.location.set_function(method_identifier);
 
   for(const auto &exception_name : m.throws_exception_table)
-    method_type.add_throws_exceptions(exception_name);
+    method_type.add_throws_exception(exception_name);
 
   const std::string signature_string = pretty_signature(method_type);
 

jbmc/src/java_bytecode/java_types.h

@@ -131,7 +131,7 @@ class java_method_typet : public code_typet
     return exceptions;
   }
 
-  void add_throws_exceptions(irep_idt exception)
+  void add_throws_exception(irep_idt exception)
   {
     add(ID_exceptions_thrown_list).get_sub().push_back(irept(exception));
   }