Add the API function that failed to the message

The sqlite::api_error class took the name of the API function that caused
the error as a parameter but did not add such information to the error
message.  I probably assumed that the message returned by the sqlite API
would be descriptive enough, but isn't.  Add the details now.

utils/sqlite/exceptions.cpp

@@ -106,7 +106,7 @@ sqlite::error::db_filename(void) const
 sqlite::api_error::api_error(const optional< fs::path >& db_filename_,
                              const std::string& api_function_,
                              const std::string& message_) :
-    error(db_filename_, message_),
+    error(db_filename_, F("%s (sqlite op: %s)") % message_ % api_function_),
     _api_function(api_function_)
 {
 }

utils/sqlite/exceptions_test.cpp

@@ -74,7 +74,9 @@ ATF_TEST_CASE_WITHOUT_HEAD(api_error__explicit);
 ATF_TEST_CASE_BODY(api_error__explicit)
 {
     const sqlite::api_error e(none, "some_function", "Some text");
-    ATF_REQUIRE_EQ("Some text (sqlite db: in-memory)", std::string(e.what()));
+    ATF_REQUIRE_EQ(
+        "Some text (sqlite op: some_function) (sqlite db: in-memory)",
+        std::string(e.what()));
     ATF_REQUIRE_EQ("some_function", e.api_function());
 }
 
@@ -96,8 +98,9 @@ ATF_TEST_CASE_BODY(api_error__from_database)
 
     const sqlite::api_error e = sqlite::api_error::from_database(
         db, "real_function");
-    ATF_REQUIRE_MATCH(".*ABCDE.*\\(sqlite db: .*/test.db\\)",
-                      std::string(e.what()));
+    ATF_REQUIRE_MATCH(
+        ".*ABCDE.*\\(sqlite op: real_function\\) \\(sqlite db: .*/test.db\\)",
+        std::string(e.what()));
     ATF_REQUIRE_EQ("real_function", e.api_function());
 }