Merge in macro

diff --git a/m4/ax_check_library.m4 b/m4/ax_check_library.m4
new file mode 100644 (file)
index 0000000..13dcfd6
--- /dev/null
+++ b/m4/ax_check_library.m4
@@ -0,0 +1,95 @@
+# ===========================================================================
+#     http://www.gnu.org/software/autoconf-archive/ax_check_library.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_LIBRARY(VARIABLE-PREFIX, HEADER-FILE, LIBRARY-FILE,
+#                    [ACTION-IF-FOUND], [ACTION-IF-NOT_FOUND])
+#
+# DESCRIPTION
+#
+#   Provides a generic test for a given library, similar in concept to the
+#   PKG_CHECK_MODULES macro used by pkg-config.
+#
+#   Most simplest libraries can be checked against simply through the
+#   presence of a header file and a library to link to. This macro allows to
+#   wrap around the test so that it doesn't have to be recreated each time.
+#
+#   Rather than define --with-$LIBRARY arguments, it uses variables in the
+#   same way that PKG_CHECK_MODULES does. It doesn't, though, use the same
+#   names, since you shouldn't provide a value for LIBS or CFLAGS but rather
+#   for LDFLAGS and CPPFLAGS, to tell the linker and compiler where to find
+#   libraries and headers respectively.
+#
+#   If the library is find, HAVE_PREFIX is defined, and in all cases
+#   PREFIX_LDFLAGS and PREFIX_CPPFLAGS are substituted.
+#
+#   Example:
+#
+#     AX_CHECK_LIBRARY([LIBEVENT], [event.h], [event], [],
+#                      [AC_MSG_ERROR([Unable to find libevent])])
+#
+# LICENSE
+#
+#   Copyright (c) 2010 Diego Elio Petteno` <flameeyes@gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 3
+
+AC_DEFUN([AX_CHECK_LIBRARY], [
+  AC_ARG_VAR($1[_CPPFLAGS], [C preprocessor flags for ]$1[ headers])
+  AC_ARG_VAR($1[_LDFLAGS], [linker flags for ]$1[ libraries])
+
+  AC_CACHE_VAL(AS_TR_SH([ax_cv_have_]$1),
+    [save_CPPFLAGS="$CPPFLAGS"
+     save_LDFLAGS="$LDFLAGS"
+     save_LIBS="$LIBS"
+
+     AS_IF([test "x$]$1[_CPPFLAGS" != "x"],
+       [CPPFLAGS="$CPPFLAGS $]$1[_CPPFLAGS"])
+
+     AS_IF([test "x$]$1[_LDFLAGS" != "x"],
+       [LDFLAGS="$LDFLAGS $]$1[_LDFLAGS"])
+
+     AC_CHECK_HEADER($2, [
+       AC_CHECK_LIB($3, [main],
+         [AS_TR_SH([ax_cv_have_]$1)=yes],
+         [AS_TR_SH([ax_cv_have_]$1)=no])
+     ], [AS_TR_SH([ax_cv_have_]$1)=no])
+
+     CPPFLAGS="$save_CPPFLAGS"
+     LDFLAGS="$save_LDFLAGS"
+     LIBS="$save_LIBS"
+    ])
+
+  AS_IF([test "$]AS_TR_SH([ax_cv_have_]$1)[" = "yes"],
+    AC_DEFINE([HAVE_]$1, [1], [Define to 1 if ]$1[ is found])
+      m4_ifnblank([$4], [$4]),
+    m4_ifnblank([$5], [$5]))
+])