ACPICA: Additional dragon_fly BSD support.

ACPICA commit 3e93431674abe947202b0f9a0afa7b625b17caa6

Makefiles and environment defines.
This commit doesn't affect Linux builds.

Link: https://github.com/acpica/acpica/commit/3e934316
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/include/acpi/platform/acenvex.h b/include/acpi/platform/acenvex.h
index 71e5ec5..14dc6f6 100644
--- a/include/acpi/platform/acenvex.h
+++ b/include/acpi/platform/acenvex.h
@@ -56,6 +56,9 @@
 #if defined(_LINUX) || defined(__linux__)
 #include <acpi/platform/aclinuxex.h>
 
+#elif defined(__DragonFly__)
+#include "acdragonflyex.h"
+
 #endif
 
 /*! [End] no source code translation !*/