build: Use ocamldep -all and -one-line flags instead of hacking the output.

We ran some sed scripts over the output of ocamldep to get them into a
single line format.  This actually broke the output of ocamldep,
combining multiple dependencies into single lines.  I didn't debug
exactly why our sed rules were broken because modern ocamldep has an
option (-one-line) which make this hacking unnecessary.

Another useful option (-all) is added so that all dependencies are
made explicit.

Since old ocamldep in RHEL 6 doesn't support these options, we have to
detect them at configure time.

The historical reason we were trying to combine entries into a single
line was so we could sort them.  That was only needed back when we
used to commit the dependency files (so the files were stable), but we
haven't committed dependency files in a long time.

m4/guestfs_ocaml.m4

@@ -56,6 +56,26 @@ AM_CONDITIONAL([HAVE_OCAMLOPT],
 AM_CONDITIONAL([HAVE_OCAMLDOC],
                [test "x$OCAMLDOC" != "xno"])
 
+dnl Check if ocamldep has options -all and -one-line (not present in RHEL 6).
+AC_MSG_CHECKING([if ocamldep has the ‘-all’ option])
+if ocamldep -all >&AS_MESSAGE_LOG_FD 2>&1; then
+    AC_MSG_RESULT([yes])
+    OCAMLDEP_ALL="-all"
+else
+    AC_MSG_RESULT([no])
+    OCAMLDEP_ALL=""
+fi
+AC_SUBST([OCAMLDEP_ALL])
+AC_MSG_CHECKING([if ocamldep has the ‘-one-line’ option])
+if ocamldep -one-line >&AS_MESSAGE_LOG_FD 2>&1; then
+    AC_MSG_RESULT([yes])
+    OCAMLDEP_ONE_LINE="-one-line"
+else
+    AC_MSG_RESULT([no])
+    OCAMLDEP_ONE_LINE=""
+fi
+AC_SUBST([OCAMLDEP_ONE_LINE])
+
 if test "x$enable_daemon" = "xyes"; then
     OCAML_PKG_hivex=no
     AC_CHECK_OCAML_PKG(hivex)

ocaml-dep.sh.in

@@ -54,9 +54,6 @@ done
 
 rm -f $output $output-t
 
-@OCAMLFIND@ ocamldep $includes "$@" |
-    @SED@ 's/ *$//' |
-    @SED@ -e :a -e '/ *\\$/N; s/ *\\\n */ /; ta' |
-    sort > $output-t
+@OCAMLFIND@ ocamldep @OCAMLDEP_ALL@ @OCAMLDEP_ONE_LINE@ $includes "$@" > $output-t
 
 mv $output-t $output