Revert "libenca: Move build host tool to PRE_BUILD_HOOKS"

This reverts commit 0644378b51f1db66ee3a09ed236f675d40dbc9d8, because
the PRE_BUILD_HOOKS support has not been merged yet.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libenca/libenca.mk

@@ -21,6 +21,6 @@ define LIBENCA_MAKE_HOST_TOOL
 	$(MAKE) -C $(@D)/tools $(HOST_CONFIGURE_OPTS) make_hash
 endef
 
-LIBENCA_PRE_BUILD_HOOKS += LIBENCA_MAKE_HOST_TOOL
+LIBENCA_POST_CONFIGURE_HOOKS += LIBENCA_MAKE_HOST_TOOL
 
 $(eval $(autotools-package))