$NetBSD: patch-configure.ac,v 1.2 2020/02/17 17:22:43 jperkin Exp $

Fix build on FreeBSD/amd64.

--- configure.ac.orig	2017-01-04 14:17:17.000000000 +0000
+++ configure.ac
@@ -732,7 +732,7 @@ dnl ** check for dtrace (currently only
 HaveDtrace=NO
 AC_PATH_PROG(DtraceCmd,dtrace)
 if test -n "$DtraceCmd"; then
-  if test "x$TargetOS_CPP-$TargetVendor_CPP" = "xdarwin-apple" -o "x$TargetOS_CPP-$TargetVendor_CPP" = "xsolaris2-unknown"; then
+  if test "x$TargetOS_CPP-$TargetVendor_CPP" = "xdarwin-apple"; then
     HaveDtrace=YES
   fi
 fi
@@ -1060,6 +1060,11 @@ if test "$ac_cv_sizeof_void_p" -eq 8 ; t
 	    # The flag MAP_NORESERVE is supported for source compatibility reasons,
 	    # but is completely ignored by OS mmap
             use_large_address_space=no
+        elif test "$ghc_host_os" = "freebsd" ; then
+            # FreeBSD doesn't support MAP_NORESERVE. The flag
+            # MAP_NORESERVE is supported for source compatibility
+            # reasons, but is completely ignored by OS mmap
+            use_large_address_space=no
         else
             AC_CHECK_DECLS([MAP_NORESERVE, MADV_FREE, MADV_DONTNEED],[],[],
                 [