Configure for OpenBSD

Index: system-autodetect.mk
--- system-autodetect.mk.orig
+++ system-autodetect.mk
@@ -61,7 +61,7 @@ endif
 #PRELOAD_MODULES=1
 
 # Flags to link with libdl.
-DL_LIBS=-ldl
+#DL_LIBS=-ldl
 
 
 ##
@@ -84,7 +84,7 @@ X11_INCLUDES:=$(shell $(PKG_CONFIG) --cflags-only-I x1
 
 # XFree86 libraries up to 4.3.0 have a bug that can cause a segfault.
 # The following setting  should  work around that situation.
-DEFINES += -DCF_XFREE86_TEXTPROP_BUG_WORKAROUND
+#DEFINES += -DCF_XFREE86_TEXTPROP_BUG_WORKAROUND
 
 # Use the Xutf8 routines (XFree86 extension) instead of the Xmb routines
 # in an UTF-8 locale. (No, you don't need this in UTF-8 locales, and
@@ -158,7 +158,7 @@ HAS_SYSTEM_ASPRINTF ?= 1
 # The following setting is needed with GNU libc for clock_gettime and the
 # monotonic clock. Other systems may not need it, or may not provide a
 # monotonic clock at all (which Ion can live with, and usually detect).
-EXTRA_LIBS += -lrt
+#EXTRA_LIBS += -lrt
 
 # Cygwin needs this. Also when you disable _BSD_SOURCE you may need it.
 #DEFINES += -DCF_NO_GETLOADAVG