use a tempfile while generating sysnum.h

Makefile.in

@@ -92,11 +92,13 @@ headers: include/bits/uClibc_config.h
 	$(Q)\
 	set -e; \
 	cd $(top_builddir); \
-	top_builddir=. CC="$(CC)" $(SHELL) extra/scripts/gen_bits_syscall_h.sh > include/bits/sysnum.h.new; \
-	if cmp include/bits/sysnum.h include/bits/sysnum.h.new >/dev/null 2>&1; then \
-		$(RM) include/bits/sysnum.h.new; \
+	tmp=`mktemp include/bits/sysnum.h.XXXXXX 2>/dev/null`; \
+	[ -z "$$tmp" ] && tmp='include/bits/sysnum.h.new'; \
+	top_builddir=. CC="$(CC)" $(SHELL) extra/scripts/gen_bits_syscall_h.sh > $$tmp; \
+	if cmp include/bits/sysnum.h $$tmp >/dev/null 2>&1; then \
+		$(RM) $$tmp; \
 	else \
-		mv -f include/bits/sysnum.h.new include/bits/sysnum.h; \
+		mv -f $$tmp include/bits/sysnum.h; \
 	fi
 ifeq ($(UCLIBC_HAS_LOCALE),y)
 	$(MAKE) locale_headers