adopt -H-all convention

Author: nikomatsakis

Makefile.in

@@ -341,7 +341,7 @@ endef
 $(foreach host,$(CFG_TARGET_TRIPLES),			\
  $(eval $(call DEF_RUSTC_TARGET,$(host))))
 
-all-rustcs: $(foreach host,$(CFG_TARGET_TRIPLES),rustc-H-$(host))
+rustc-H-all: $(foreach host,$(CFG_TARGET_TRIPLES),rustc-H-$(host))
 
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 # Entrypoint rule