On FreeBSD check and use gmake, use make elsewhere

Makefile

@@ -10,6 +10,8 @@
 include config.make
 
 INSTALL ?= cp -u -L
+MAKE ?= $_
+export MAKE
 
 ifndef NO_REBUILD_OPA_PACKAGES
 OPAOPT += "--rebuild"

README

@@ -21,7 +21,7 @@ $ sudo make install
 
 should get you there. ./configure should report any missing dependencies and
 point you to the packages you may install to fix them (although those may depend
-on your distribution).
+on your distribution). make needs to be GNU make.
 
 The main dependency of OPA is OCaml 3.12. In case your distribution doesn't
 provide a recent enough version, or if you miss some other dependencies, you can

config.mli

@@ -63,6 +63,9 @@ val is_release : bool
 type os = Linux | Mac | Win32 | Cygwin | FreeBSD
 val os : os
 
+(** the name of the  GNU make binary, gmake on fBSD, make on other platforms *)
+val makebinary : string
+
 (** the installation directory of external libraries, as in the ocamlopt '-I'
     command-line option ; None if no extra include directory is needed *)
 module Libdir : sig

configure

@@ -176,6 +176,16 @@ if [ -n "${IS_MAC:-}" ]; then
     . ./platform_helper.sh
 fi
 
+if [ -n "${IS_FREEBSD:-}" ]; then
+    echo-check gmake
+    if which gmake >/dev/null 2>&1; then echo-ok ok
+    else
+        echo-err Not found
+        echo "Please install port devel/gmake."
+        exit 1
+    fi >&2
+fi
+
 # check ocaml version and location
 echo-check ocamlopt
 if OCAMLOPT=${OCAMLOPT:-$(which ocamlopt.opt)} || OCAMLOPT=${OCAMLOPT:-$(which ocamlopt)}
@@ -650,6 +660,12 @@ let os =
     else echo 'match Sys.os_type with "Win32" -> Win32 | "Cygwin" -> Cygwin | _ -> assert false'
     fi)
 
+let makebinary =
+  $(if [ -n "${IS_FREEBSD:-}" ];
+   then echo '"gmake"'
+   else echo '"make"'
+   fi)
+
 module Libdir = struct
   let ssl = $(dir_opt "$CONFIG_LIB_OCAMLSSL")
   let cryptokit = $(dir_opt "$CONFIG_LIB_CRYPTOKIT")

qml2ocaml/qml2ocaml.ml

@@ -703,7 +703,7 @@ prerr_endline \"CHECKUP - LIBS - OK\"
     in
 
     let compilation_via_makefile =
-      let make = Printf.sprintf "make --makefile=%s -W %s -j %d %s" target_makefile target_makefile options.O.makefile_max_jobs
+      let make = Printf.sprintf "%s --makefile=%s -W %s -j %d %s" Config.makebinary target_makefile target_makefile options.O.makefile_max_jobs
         (match options.O.makefile_rule with
         | O.Bytecode ->
             (match ObjectFiles.compilation_mode () with