m4: provide additional pkg-config macros

The macros provide a succint way to run a pkg-config check over modules
depending on a --with-name configure option.

There is a flexible variant to have custom behaviour if the package is
found or not and two more limited ones that just set HAVE_NAME make and
preprocessor variables.

pkg.m4

@@ -157,3 +157,77 @@ else
 	$3
 fi[]dnl
 ])# PKG_CHECK_MODULES
+
+# PKG_WITH_MODULES(VARIABLE-PREFIX, MODULES,
+#                  [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND],
+#                  [DESCRIPTION], [DEFAULT])
+#
+# Prepare a "--with-" configure option using the lowercase [VARIABLE-PREFIX]
+# name, merging the behaviour of AC_ARG_WITH and PKG_CHECK_MODULES in a single
+# macro
+#
+# --------------------------------------------------------------
+AC_DEFUN([PKG_WITH_MODULES],
+[
+m4_pushdef([with_arg], m4_tolower([$1]))
+
+m4_pushdef([description],
+           [m4_default([$5], [build with ]with_arg[ support])])
+
+m4_pushdef([def_arg], [m4_default([$6], [auto])])
+m4_pushdef([def_action_if_found], [AS_TR_SH([with_]with_arg)=yes])
+m4_pushdef([def_action_if_not_found], [AS_TR_SH([with_]with_arg)=no])
+
+m4_case(def_arg,
+            [yes],[m4_pushdef([with_without], [--without-]with_arg)],
+            [m4_pushdef([with_without],[--with-]with_arg)])
+
+AC_ARG_WITH(with_arg,
+     AS_HELP_STRING(with_without, description[ @<:@default=]def_arg[@:>@]),,
+    [AS_TR_SH([with_]with_arg)=def_arg])
+
+AS_CASE([$AS_TR_SH([with_]with_arg)],
+            [yes],[PKG_CHECK_MODULES([$1],[$2],$3,$4)],
+            [auto],[PKG_CHECK_MODULES([$1],[$2],
+                                        [m4_n([def_action_if_found]) $3],
+                                        [m4_n([def_action_if_not_found]) $4])])
+
+m4_popdef([with_arg])
+m4_popdef([description])
+m4_popdef([def_arg])
+
+]) dnl PKG_WITH_MODULES
+
+# PKG_HAVE_WITH_MODULES(VARIABLE-PREFIX, MODULES,
+#                       [DESCRIPTION], [DEFAULT])
+#
+# Convenience macro to trigger AM_CONDITIONAL after
+# PKG_WITH_MODULES check.
+#
+# HAVE_[VARIABLE-PREFIX] is exported as make variable.
+#
+# --------------------------------------------------------------
+AC_DEFUN([PKG_HAVE_WITH_MODULES],
+[
+PKG_WITH_MODULES([$1],[$2],,,[$3],[$4])
+
+AM_CONDITIONAL([HAVE_][$1],
+               [test "$AS_TR_SH([with_]m4_tolower([$1]))" = "yes"])
+])
+
+# PKG_HAVE_DEFINE_WITH_MODULES(VARIABLE-PREFIX, MODULES,
+#                              [DESCRIPTION], [DEFAULT])
+#
+# Convenience macro to run AM_CONDITIONAL and AC_DEFINE after
+# PKG_WITH_MODULES check.
+#
+# HAVE_[VARIABLE-PREFIX] is exported as make and preprocessor variable.
+#
+# --------------------------------------------------------------
+AC_DEFUN([PKG_HAVE_DEFINE_WITH_MODULES],
+[
+PKG_HAVE_WITH_MODULES([$1],[$2],[$3],[$4])
+
+AS_IF([test "$AS_TR_SH([with_]m4_tolower([$1]))" = "yes"],
+        [AC_DEFINE([HAVE_][$1], 1, [Enable ]m4_tolower([$1])[ support])])
+])