ENH: Propagate cmake variables to macros in C

Source/cmConfigure.cmake.h.in

@@ -2,6 +2,8 @@
 #cmakedefine CMAKE_NO_ANSI_STREAM_HEADERS
 #cmakedefine CMAKE_NO_ANSI_STRING_STREAM
 #cmakedefine CMAKE_NO_ANSI_FOR_SCOPE
+#cmakedefine HAVE_ENVIRON_NOT_REQUIRE_PROTOTYPE
+#cmakedefine HAVE_UNSETENV
 #define  CMAKE_ROOT_DIR "${CMake_SOURCE_DIR}"
 #define  CMAKE_BUILD_DIR "${CMake_BINARY_DIR}"
 #define  CMAKE_PREFIX "${CMAKE_INSTALL_PREFIX}"