[PATCH v2 libinput] Add configure.ac check for static_assert

[Baruch Siach]

Hi Peter,

On Mon, May 16, 2016 at 01:32:07PM +1000, Peter Hutterer wrote:
> Part of C11, defined via assert.h.
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>

This fixes the build using a uClibc-ng toolchain that does not define the 
static_assert macro.

Tested-by: Baruch Siach <baruch at tkos.co.il>

Thanks,
baruch

> ---
> Changes to v1: 
> - leave static_assert in place and just check for that in configure
> 
>  configure.ac | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/configure.ac b/configure.ac
> index 8ddc3b6..8c14efe 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -59,6 +59,10 @@ AC_CHECK_DECL(TFD_CLOEXEC,[],
>  AC_CHECK_DECL(CLOCK_MONOTONIC,[],
>  	      [AC_MSG_ERROR("CLOCK_MONOTONIC is needed to compile libinput")],
>  	      [[#include <time.h>]])
> +AC_CHECK_DECL(static_assert, [],
> +	      [AC_DEFINE(static_assert(...), [/* */], [noop static_assert() replacement]),
> +              AC_MSG_RESULT([no])],
> +	      [[#include <assert.h>]])
>  
>  PKG_PROG_PKG_CONFIG()
>  PKG_CHECK_MODULES(MTDEV, [mtdev >= 1.1.0])
> -- 
> 2.7.4
> 

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