CTest: adopt std::chrono::system_clock

After the refactor to make CTest use std::chrono::steady_clock for the
keeping of time for test duration, there are still references to
cmSystemTools::GetTime() left.
To further adopt std::chrono for time related activities, this commit
changes those remaining references to std::chrono::system_clock::now()
calls and alters the storage from either unsigned int or double to
std::chrono::system_clock::time_point.

For ease of conversion, a converter method is added to cmXMLWriter that
converts from a std::chrono::system_clock::time_point to the number of
seconds since the UN*X epoch as that is expected behaviour. This means
no more casts as required.

Functionally should be no difference as the system_clock is implemented
in the same terms.

1 files changed, 2 insertions, 2 deletions

diff --git a/Source/CTest/cmCTestBuildHandler.h b/Source/CTest/cmCTestBuildHandler.h
index 9a29d6d..d1b9b2e 100644
--- a/Source/CTest/cmCTestBuildHandler.h
+++ b/Source/CTest/cmCTestBuildHandler.h
@@ -94,8 +94,8 @@ private:
 
   std::string StartBuild;
   std::string EndBuild;
-  double StartBuildTime;
-  double EndBuildTime;
+  std::chrono::system_clock::time_point StartBuildTime;
+  std::chrono::system_clock::time_point EndBuildTime;
 
   std::vector<std::string> CustomErrorMatches;
   std::vector<std::string> CustomErrorExceptions;