i#5888: Avoid fatal error on lib copy collision (#7264)

Switches from "cmake -E copy" to "cmake -E copy_if_different" for the
Windows library copies used for API standalone tests. We have seen
sporadic fatal errors from drconfiglib.dll failing to copy, presumably
because another rule already copied it. It has proven difficult to
figure out which rules are colliding, so we solve this by making it a
non-fatal error.

Fixes #5888

Author: derekbruening

suite/tests/CMakeLists.txt

@@ -970,15 +970,19 @@ function(add_api_exe test source use_decoder use_static_DR)
         COMMAND ${CMAKE_COMMAND} ARGS
           -E touch "${drcopy_stamp}"
         COMMAND ${CMAKE_COMMAND} ARGS
-          -E copy "${MAIN_LIBRARY_OUTPUT_DIRECTORY}/dynamorio.dll"
+          -E copy_if_different "${MAIN_LIBRARY_OUTPUT_DIRECTORY}/dynamorio.dll"
           "${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/dynamorio.dll"
         # libutil.drconfig_test needs drconfiglib.
         COMMAND ${CMAKE_COMMAND} ARGS
-          -E copy "${MAIN_LIBRARY_OUTPUT_DIRECTORY}/../drconfiglib.dll"
+          # XXX i#5888: There is a race somewhere causing this copy to sometimes
+          # fail, presumably because another target already copied it.  We use
+          # copy_if_different to avoid failure if it exists, here and in the other
+          # copy commands above and below.
+          -E copy_if_different "${MAIN_LIBRARY_OUTPUT_DIRECTORY}/../drconfiglib.dll"
           "${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/drconfiglib.dll"
         # We copy drsyms.dll too, for api.symtest
         COMMAND ${CMAKE_COMMAND} ARGS
-          -E copy "${PROJECT_BINARY_DIR}/ext/${INSTALL_LIB}/drsyms.dll"
+          -E copy_if_different "${PROJECT_BINARY_DIR}/ext/${INSTALL_LIB}/drsyms.dll"
           "${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/drsyms.dll"
         VERBATIM)
       add_custom_target(drcopy DEPENDS "${drcopy_stamp}")