Log Message:
cmake: update to 3.9.3

Changes in 3.9.3 since 3.9.2:
* VS: Do not consider MAP_IMPORTED_CONFIG_ on non-imported targets
  bootstrap: Fix running multiple times in-source
* vim: Remove default setting of expandtab
* FindBoost: Add support for Boost 1.65.0 and 1.65.1 to CMake 3.9
* CTest: fix crash if source file for coverage cannot be found
* Autogen: Backport autogen target dependency as file dependency fix
* Autogen: Tests: Backport tests for _autogen target dependencies