auto merge of #13581 : DiamondLovesYou/rust/tests-mk-typo, r=alexcrichton

I spotted this while working on #13450.

Author: bors

mk/tests.mk

@@ -568,7 +568,7 @@ CTEST_COMMON_ARGS$(1)-T-$(2)-H-$(3) :=						\
         --host $(3)                                       \
         --adb-path=$(CFG_ADB)                          \
         --adb-test-dir=$(CFG_ADB_TEST_DIR)                  \
-        --host-rustcflags "$(RUSTC_FLAGS_$(3)) $$(CTEST_RUSTC_FLAGS) -L $$(RT_OUTPUT_DIR_$(2))" \
+        --host-rustcflags "$(RUSTC_FLAGS_$(3)) $$(CTEST_RUSTC_FLAGS) -L $$(RT_OUTPUT_DIR_$(3))" \
         --target-rustcflags "$(RUSTC_FLAGS_$(2)) $$(CTEST_RUSTC_FLAGS) -L $$(RT_OUTPUT_DIR_$(2))" \
         $$(CTEST_TESTARGS)