tools/build: remove usage of sed -i

The "-i" sed option is not POSIX compatible [0], remove it's usage and
instead create yet another temporary intermediate file.

[0] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

tools/include/xen-foreign/Makefile

@@ -36,8 +36,9 @@ x86_32.h: mkheader.py structs.py $(ROOT)/arch-x86/xen-x86_32.h $(ROOT)/arch-x86/
 x86_64.h: mkheader.py structs.py $(ROOT)/arch-x86/xen-x86_64.h $(ROOT)/arch-x86/xen.h $(ROOT)/xen.h
 	$(PYTHON) $< $* $@.tmp $(filter %.h,$^)
 	#Avoid mixing an alignment directive with a uint64_t cast or sizeof expression
-	sed 's/(__align8__ \(u\?int64_t\))/(\1)/g' -i $@.tmp
-	$(call move-if-changed,$@.tmp,$@)
+	sed 's/(__align8__ \(u\?int64_t\))/(\1)/g' < $@.tmp > $@.tmp2
+	rm $@.tmp
+	$(call move-if-changed,$@.tmp2,$@)
 
 checker.c: mkchecker.py structs.py
 	$(PYTHON) $< $@ $(architectures)