ARM - pass linker flags along to the linker

On the ARM toolchain linker flags specified in the build profile do
not get passed to armlink. This patch adds these flags to the
arguments sent to armlink.

tools/toolchains/arm.py

@@ -179,6 +179,8 @@ class ARM(mbedToolchain):
         else:
             args = ["-o", output, "--info=totals", "--map", "--list=%s" % map_file]
 
+        args.extend(self.flags['ld'])
+
         if mem_map:
             args.extend(["--scatter", mem_map])