kbuild: distcc/icecc might not handle input from stdin correctly

Not all versions distcc/icecc handle input from stdin correctly. Use
the temporary file to avoid that. It leads to ever changing compiler
options and therefor to full recompiles.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

scripts/Kbuild.include

@@ -98,8 +98,9 @@ as-option = $(call try-run,\
 # as-instr
 # Usage: cflags-y += $(call as-instr,instr,option1,option2)
 
-as-instr = $(call try-run,\
-	echo -e "$(1)" | $(CC) $(KBUILD_AFLAGS) -c -xassembler -o "$$TMP" -,$(2),$(3))
+as-instr = $(call try-run,		\
+	echo -e "$(1)" > "$$TMP"; 	\
+	$(CC) $(KBUILD_AFLAGS) -c -xassembler -o /dev/null "$$TMP",$(2),$(3))
 
 # cc-option
 # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)