infra: add to luarocks support for top-level parallel make

The host-luarock dependency is not always satisfied for the extract
phase because the %-extract target is not anymore in the dependency
chain.
To be sure that the dependency is satisfied add the dependency to the
stamp file $(%_TARGET_EXTRACT) instead of the %-extract target.

Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Cc: Francois Perrad <fperrad@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/pkg-luarocks.mk

@@ -43,10 +43,6 @@ $(2)_SITE		?= $(call qstrip,$(BR2_LUAROCKS_MIRROR))
 # a target package, and can just add the required dependencies
 $(2)_DEPENDENCIES	+= host-luarocks luainterpreter
 
-# $(2)_DEPENDENCIES are handled for configure step (too late)
-# but host-luarocks is required to do the extract
-$(1)-extract: host-luarocks
-
 #
 # Extract step
 #
@@ -71,6 +67,10 @@ endif
 # make targets
 $(call inner-generic-package,$(1),$(2),$(3),$(4))
 
+# $(2)_DEPENDENCIES are handled for configure step (too late)
+# but host-luarocks is required to do the extract
+$$($(2)_TARGET_EXTRACT): | host-luarocks
+
 endef
 
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