Fix compiling on 32 bit x86.
Change-Id: I6210573e1d9287ac49acbe3d7e5181e309316107
VP8_CX_SRCS-$(HAVE_SSE4_1) += encoder/x86/sad_sse4.asm
VP8_CX_SRCS-$(ARCH_X86)$(ARCH_X86_64) += encoder/x86/quantize_mmx.asm
VP8_CX_SRCS-$(ARCH_X86)$(ARCH_X86_64) += encoder/x86/encodeopt.asm
-VP8_CX_SRCS-$(ARCH_X86)$(ARCH_X86_64) += encoder/x86/ssim_opt.asm
+VP8_CX_SRCS-$(ARCH_X86_64) += encoder/x86/ssim_opt.asm
ifeq ($(CONFIG_REALTIME_ONLY),yes)
VP8_CX_SRCS_REMOVE-$(HAVE_SSE2) += encoder/x86/temporal_filter_apply_sse2.asm