[Buildroot] autobuilder toolchain updates

Hello,

I have just pushed an update of several pre-built Buildroot toolchains
used in the autobuilders:

     * br-aarch64-glibc.config
    
       Only rebuilt because uses a custom binutils version, and the
       binutils options have been renamed.
    
     * br-arcle-hs38.config
    
       Rebuilt to use the latest ARC toolchain updates.
    
     * br-arm-cortex-a9-glibc.config
    
       Rebuilt to use binutils 2.25.1.
    
     * br-arm-cortex-a9-musl.config
    
       Only rebuilt because uses a custom binutils version, and the
       binutils options have been renamed.
    
     * br-arm-full.config
    
       Rebuilt to use 3.10 kernel headers instead of the latest, so that
       we have one toolchain with reasonably ancient/recent kernel
       headers.
    
     * br-mips64-n64-glibc.config
    
       Only rebuilt because uses a custom binutils version, and the
       binutils options have been renamed.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com