Allow overriding the linker

This patch allows the user to override the value of the LD Makefile
variable. This feature can be used to force the use of the new Clang
linker.

Change-Id: I97ffeb18e48fa75346702a479d7dc1e8abcb3621
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>
1 file changed