CMake - remove parameter repetition in else() and endif() statements

This follows Professional CMake's recommended practises

libgnucash/backend/sql/CMakeLists.txt

@@ -81,4 +81,4 @@ if(WITH_SQL)
     RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
 
   # No headers to install
-endif(WITH_SQL)
+endif()

libgnucash/backend/sql/test/CMakeLists.txt

@@ -24,4 +24,4 @@ if(WITH_SQL)
     BACKEND_SQL_TEST_INCLUDE_DIRS BACKEND_SQL_TEST_LIBS
   )
   target_compile_definitions(test-sqlbe PRIVATE TESTPROG=test_sqlbe)
-endif(WITH_SQL)
+endif()