Remove bash-ism from configure script.
Disable udev/systemd detection for *BSD as the catch-all assumes a Linux
system. A configuration file for devd(8) is provided by this port instead.

--- configure.ac.orig	2020-06-09 02:57:16 UTC
+++ configure.ac
@@ -36,7 +36,7 @@ if test "x$have_limd" = "xyes"; then
     AC_SUBST(libimobiledevice_CFLAGS)
     AC_SUBST(libimobiledevice_LIBS)
     CACHED_CFLAGS="$CFLAGS"
-    CFLAGS+=" $libimobiledevice_CFLAGS"
+    CFLAGS="$CFLAGS $libimobiledevice_CFLAGS"
     AC_CACHE_CHECK(for enum idevice_connection_type, ac_cv_enum_idevice_connection_type,
       AC_TRY_COMPILE([
         #include <libimobiledevice/libimobiledevice.h>
@@ -125,7 +125,7 @@ case ${host_os} in
     AC_SUBST(WINDRES)
     activation_method="manual"
     ;;
-  darwin*)
+  darwin*|dragonfly*|*bsd*)
     win32=false
     AC_MSG_RESULT([no])
     # No support for launchd yet