arm: fix compilation on ARMv7

/tmp/ccq2xzf8.s: Assembler messages:
/tmp/ccq2xzf8.s:5748: Error: thumb conditional instruction should be in IT block -- strexeq r1,r2,[r3]'

Cc: Alexander Kartashov <alekskartashov@parallels.com>
Cc: Ruslan Kuprieiv <kupruser@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Makefile

@@ -64,6 +64,8 @@ ifeq ($(shell echo $(ARCH) | sed -e 's/arm.*/arm/'),arm)
 	SRCARCH      := arm
 	DEFINES      := -DCONFIG_ARMV$(ARMV)
 
+	USERCFLAGS += -Wa,-mimplicit-it=always
+
 	ifeq ($(ARMV),6)
 		USERCFLAGS += -march=armv6
 	endif