Fix build on BSD

Removed the line `SHELL:=/usr/bin/env bash'. Most BSDs don't ship bash in the
base system by default and the build doesn't need it anyway.

Also added some more version statements to define useXDG for the other BSDs.

makefile

@@ -86,8 +86,6 @@ else ifneq (,$(findstring gdc, $(DC)))
 	WRITE_TO_TARGET_NAME = -o $@
 endif
 
-SHELL:=/usr/bin/env bash
-
 GITHASH = bin/githash.txt
 
 

src/dscanner/main.d

@@ -574,6 +574,9 @@ private enum CONFIG_FILE_NAME = "dscanner.ini";
 version (linux) version = useXDG;
 version (BSD) version = useXDG;
 version (FreeBSD) version = useXDG;
+version (OpenBSD) version = useXDG;
+version (NetBSD) version = useXDG;
+version (DragonflyBSD) version = useXDG;
 version (OSX) version = useXDG;
 
 /**