x86emul: inherit HOSTCC when building 32-bit harness on 64-bit host

We're deliberately bringing XEN_COMPILE_ARCH and XEN_TARGET_ARCH out of
sync in this case, and hence HOSTCC won't get set from CC. Therefore
without this addition HOSTCC would not match a possible make command
line override of CC, but default to "gcc", likely causing the build to
fail for test_x86_emulator.c on systems with too old a gcc.

Signed-off-by: Jan Beulich <[email protected]>
Acked-by: Andrew Cooper <[email protected]>

tools/tests/x86_emulator/Makefile

@@ -268,7 +268,7 @@ install uninstall:
 ifeq ($(XEN_COMPILE_ARCH),x86_64)
 run32: $(addsuffix .h,$(TESTCASES)) $(addsuffix -opmask.h,$(OPMASK))
 run32 clean32: %32:
-	$(MAKE) -C 32 $*
+	$(MAKE) -C 32 HOSTCC=$(HOSTCC) $*
 clean: clean32
 else
 run32 clean32: %32: %