Merge pull request #20 from tompng/sync_windows_clock_id

Sync ruby/ruby#14866

Author: hsbt

lib/core_assertions.rb

@@ -835,6 +835,9 @@ def assert_all_assertions_foreach(msg = nil, *keys, &block)
             rescue
               # Constants may be defined but not implemented, e.g., mingw.
             else
+              unless Process.clock_getres(clk) < 1.0e-03
+                next # needs msec precision
+              end
               PERFORMANCE_CLOCK = clk
             end
           end