build/nmk: rename $@-ldflags-y to LDFLAGS_$@

That will complement existing CFLAGS_ and ASFLAGS_.
As no one use it yet (I will use it, do not remove) - no need
for convert-everything patch.

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

scripts/nmk/scripts/build.mk

@@ -105,7 +105,7 @@ define gen-custom-target-rule
         ifneq ($($(1)-obj-y),)
                 $(eval $(call gen-ld-target-rule,                       \
                                 $(obj)/$(1).built-in.o,                 \
-                                $(ld_flags) $($(1)-ldflags-y),          \
+                                $(ld_flags) $(LDFLAGS_$(1)),            \
                                 $(call objectify,$($(1)-obj-y)),        \
                                 $(call objectify,$($(1)-obj-y))         \
                                 $(call objectify,$($(1)-obj-e))))