kbuild: add KBUILD_HOSTLDFLAGS to cmd_host-csingle

When compiling executables from a single.c file, the linker is also
invoked. Pass the flags like the other linker commands.

cherry-pick kbuild change from Linux:

63185b46cdb3 (kbuild: use HOSTLDFLAGS for single .c executables)

Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index 69983a1..7624304 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -89,7 +89,7 @@
 # Create executable from a single .c file
 # host-csingle -> Executable
 quiet_cmd_host-csingle 	= HOSTCC  $@
-      cmd_host-csingle	= $(HOSTCC) $(hostc_flags) -o $@ $< \
+      cmd_host-csingle	= $(HOSTCC) $(hostc_flags) $(KBUILD_HOSTLDFLAGS) -o $@ $< \
 	  	$(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(@F))
 $(host-csingle): $(obj)/%: $(src)/%.c FORCE
 	$(call if_changed_dep,host-csingle)