Modernise some parameters.

Following suggestions from clant-tidy.

include/pqxx/except.hxx

@@ -137,8 +137,8 @@ class PQXX_LIBEXPORT sql_error : public failure
 
 public:
   explicit sql_error(
-    std::string whatarg = "", std::string const &Q = "",
-    char const sqlstate[] = nullptr
+    std::string const &whatarg = "", std::string Q = "",
+    char const *sqlstate = nullptr
 #if defined(PQXX_HAVE_SOURCE_LOCATION)
     ,
     std::source_location = std::source_location::current()

include/pqxx/row.hxx

@@ -215,7 +215,7 @@ public:
 protected:
   friend class const_row_iterator;
   friend class result;
-  row(result const &r, result_size_type index, size_type cols) noexcept;
+  row(result r, result_size_type index, size_type cols) noexcept;
 
   /// Throw @ref usage_error if row size is not `expected`.
   void check_size(size_type expected) const

src/except.cxx

@@ -83,20 +83,19 @@ pqxx::variable_set_to_null::variable_set_to_null(
 
 
 pqxx::sql_error::sql_error(
-  std::string whatarg, std::string const &Q, char const sqlstate[]
+  std::string const &whatarg, std::string Q, char const *sqlstate
 #if defined(PQXX_HAVE_SOURCE_LOCATION)
   ,
   std::source_location loc
 #endif
   ) :
-        failure{
-          std::move(whatarg)
+        failure{whatarg
 #if defined(PQXX_HAVE_SOURCE_LOCATION)
             ,
           loc
 #endif
         },
-        m_query{Q},
+        m_query{std::move(Q)},
         m_sqlstate{sqlstate ? sqlstate : ""}
 {}
 

src/row.cxx

@@ -28,8 +28,8 @@ extern "C"
 
 
 pqxx::row::row(
-  result const &r, result::size_type index, size_type cols) noexcept :
-        m_result{r}, m_index{index}, m_end{cols}
+  result r, result::size_type index, size_type cols) noexcept :
+        m_result{std::move(r)}, m_index{index}, m_end{cols}
 {}