mk: Fix native LLVM deps for cross-host builds

We use a script called `mklldeps.py` to run `llvm-config` to generate a list
of LLVM libraries and native dependencies needed by LLVM, but all cross-compiled
LLVM builds were using the *host triple's* `llvm-config` instead of the
*target's* `llvm-config`. This commit alters this to require the right
`llvmdeps.rs` to be generated which will run the correct `llvm-config`.

Author: alexcrichton

mk/llvm.mk

@@ -66,7 +66,7 @@ $(foreach host,$(CFG_HOST), \
 
 # This can't be done in target.mk because it's included before this file.
 define LLVM_LINKAGE_DEPS
-$$(TLIB$(1)_T_$(2)_H_$(3))/stamp.rustc_llvm: $$(LLVM_LINKAGE_PATH_$(3))
+$$(TLIB$(1)_T_$(2)_H_$(3))/stamp.rustc_llvm: $$(LLVM_LINKAGE_PATH_$(2))
 endef
 
 $(foreach source,$(CFG_HOST), \

mk/target.mk

@@ -83,7 +83,7 @@ $$(TLIB$(1)_T_$(2)_H_$(3))/stamp.$(4): \
 	    $$(dir $$@)$$(call CFG_LIB_GLOB_$(2),$(4)))
 	$$(call REMOVE_ALL_OLD_GLOB_MATCHES, \
 	    $$(dir $$@)$$(call CFG_RLIB_GLOB,$(4)))
-	$(Q)CFG_LLVM_LINKAGE_FILE=$$(LLVM_LINKAGE_PATH_$(3)) \
+	$(Q)CFG_LLVM_LINKAGE_FILE=$$(LLVM_LINKAGE_PATH_$(2)) \
 	    $$(subst @,,$$(STAGE$(1)_T_$(2)_H_$(3))) \
 		$$(RUST_LIB_FLAGS_ST$(1)) \
 		-L "$$(RT_OUTPUT_DIR_$(2))" \

mk/tests.mk

@@ -382,7 +382,7 @@ $(3)/stage$(1)/test/$(4)test-$(2)$$(X_$(2)): \
 		$$(CRATEFILE_$(4)) \
 		$$(TESTDEP_$(1)_$(2)_$(3)_$(4))
 	@$$(call E, rustc: $$@)
-	$(Q)CFG_LLVM_LINKAGE_FILE=$$(LLVM_LINKAGE_PATH_$(3)) \
+	$(Q)CFG_LLVM_LINKAGE_FILE=$$(LLVM_LINKAGE_PATH_$(2)) \
 	    $$(subst @,,$$(STAGE$(1)_T_$(2)_H_$(3))) -o $$@ $$< --test \
 		-L "$$(RT_OUTPUT_DIR_$(2))" \
 		$$(LLVM_LIBDIR_RUSTFLAGS_$(2)) \
@@ -894,7 +894,7 @@ ifeq ($(2),$$(CFG_BUILD))
 $$(call TEST_OK_FILE,$(1),$(2),$(3),doc-crate-$(4)): $$(CRATEDOCTESTDEP_$(1)_$(2)_$(3)_$(4))
 	@$$(call E, run doc-crate-$(4) [$(2)])
 	$$(Q)touch $$@.start_time
-	$$(Q)CFG_LLVM_LINKAGE_FILE=$$(LLVM_LINKAGE_PATH_$(3)) \
+	$$(Q)CFG_LLVM_LINKAGE_FILE=$$(LLVM_LINKAGE_PATH_$(2)) \
 	    $$(RUSTDOC_$(1)_T_$(2)_H_$(3)) --test --cfg dox \
 	        $$(CRATEFILE_$(4)) --test-args "$$(TESTARGS)" && \
 	        touch -r $$@.start_time $$@ && rm $$@.start_time