Remove timer.cpp as implementation is now inline.

[SVN r8569]

libs/regression.cfg

@@ -28,7 +28,6 @@ compile-fail libs/static_assert/static_assert_test_fail_5.cpp
 compile-fail libs/static_assert/static_assert_test_fail_6.cpp
 compile-fail libs/static_assert/static_assert_test_fail_7.cpp
 compile-fail libs/static_assert/static_assert_test_fail_8.cpp
-compile libs/timer/timer.cpp
 compile libs/timer/timer_test.cpp
 compile libs/utility/call_traits_test.cpp
 compile libs/utility/compressed_pair_test.cpp