Patch merged into coreboot/master: 1b7c959 crossgcc: don't use libdl while building GDB on FreeBSD

the following patch was just integrated into master:
commit 1b7c9590f4bcbb82cbea7cdbbf9d423086c96b35
Author: Idwer Vollering 
Date:   Thu Apr 9 15:34:07 2015 +0200

crossgcc: don't use libdl while building GDB on FreeBSD

Since FreeBSD doesn't have libdl, these errors are shown:
    - config.log: /usr/bin/ld: cannot find -ldl
    - crossgcc-build.log: configure: error: C compiler cannot create executables

Conditionally pass the presence of libdl in LDFLAGS.

Change-Id: I79c48da7e6700a4606c9e0c1314241db8997d3f3
    Signed-off-by: Idwer Vollering 
    Reviewed-on: http://review.coreboot.org/2342
    Tested-by: build bot (Jenkins)
    Reviewed-by: Patrick Georgi

See http://review.coreboot.org/2342 for details.

-gerrit