add missing cap-ng.m4

missing from 11cacc6

.gitignore

@@ -1,7 +1,11 @@
 # out-of-tree build
 build/
 # autoconf
-m4/
+m4/libtool.m4
+m4/ltoptions.m4
+m4/ltsugar.m4
+m4/ltversion.m4
+m4/lt~obsolete.m4
 Makefile.in
 aclocal.m4
 autom4te.cache

m4/cap-ng.m4

@@ -0,0 +1,40 @@
+# libcap-ng.m4 - Checks for the libcap-ng support
+# 	Copyright (c) 2009 Steve Grubb [email protected]
+#
+AC_DEFUN([LIBCAP_NG_PATH],
+[
+  AC_ARG_WITH(libcap-ng,
+    [  --with-libcap-ng=[auto/yes/no]  Add Libcap-ng support [default=auto]],,
+    with_libcap_ng=auto)
+
+  # Check for Libcap-ng API
+  #
+  # libcap-ng detection
+
+  if test x$with_libcap_ng = xno ; then
+      have_libcap_ng=no;
+  else
+      # Start by checking for header file
+      AC_CHECK_HEADER(cap-ng.h, capng_headers=yes, capng_headers=no)
+
+      # See if we have libcap-ng library
+      AC_CHECK_LIB(cap-ng, capng_clear,
+	         CAPNG_LDADD=-lcap-ng,)
+
+      # Check results are usable
+      if test x$with_libcap_ng = xyes -a x$CAPNG_LDADD = x ; then
+         AC_MSG_ERROR(libcap-ng support was requested and the library was not found)
+      fi
+      if test x$CAPNG_LDADD != x -a $capng_headers = no ; then
+         AC_MSG_ERROR(libcap-ng libraries found but headers are missing)
+      fi
+  fi
+  AC_SUBST(CAPNG_LDADD)
+  AC_MSG_CHECKING(whether to use libcap-ng)
+  if test x$CAPNG_LDADD != x ; then
+      AC_DEFINE(HAVE_LIBCAP_NG,1,[libcap-ng support])
+      AC_MSG_RESULT(yes)
+  else
+      AC_MSG_RESULT(no)
+  fi
+])