[Beignet] [PATCH] Make FindLLVM.cmake work with empty "system-libs"

[Yang, Rong R]

Because beignet link with the LLVM static libraries, and system-libs is required by LLVM libraries.
If Gentoo wipe "system-libs", do you know LLVM how to find this libraries?

> -----Original Message-----
> From: Beignet [mailto:beignet-bounces at lists.freedesktop.org] On Behalf Of
> Steven Newbury
> Sent: Thursday, December 17, 2015 7:33
> To: beignet at lists.freedesktop.org
> Subject: [Beignet] [PATCH] Make FindLLVM.cmake work with empty
> "system-libs"
> 
> On Gentoo we sanitise and fix up llvm-config to work with shared libraries
> and to provide correct output for @world to build against.
>  (See https://bugs.gentoo.org/show_bug.cgi?id=565358) Part of this is we
> wipe "system-libs" since it's inappropriate to link to unnecessarily.
> 
> This has revealed the FindLLVM.cmake included with Beignet fails when
> system-libs is empty.  Attached patch fixes this by checking for a result
> before calling REGEX.