cmstd: Modernize CMake system headers

Provide a standardized way to handle the C++ "standard" headers
customized to be used with current CMake C++ standard constraints.
Offer under directory `cm` headers which can be used as direct
replacements of the standard ones.  For example:

    #include <cm/string_view>

can be used safely for CMake development in place of the `<string_view>`
standard header.

Fixes: #19491

1 files changed, 1 insertions, 1 deletions

diff --git a/Source/CTest/cmCTestStartCommand.h b/Source/CTest/cmCTestStartCommand.h
index 7c71f36..598c937 100644
--- a/Source/CTest/cmCTestStartCommand.h
+++ b/Source/CTest/cmCTestStartCommand.h
@@ -13,7 +13,7 @@
 #include <utility>
 #include <vector>
 
-#include "cm_memory.hxx"
+#include <cm/memory>
 
 class cmExecutionStatus;