arm: fix missing dependency with --enable-shared

The C version of the dequant/idct/add function depends on the C
version of the IDCT, but this isn't compiled in on ARM. Since this
code has asm version, we can just remove this file to eliminate the
link error.

Change-Id: I21de74d89d3765a1db2da27292b20727c53178e9

vp8/vp8dx_arm.mk

@@ -14,6 +14,7 @@
 VP8_DX_SRCS-$(HAVE_ARMV6)  += decoder/arm/dequantize_arm.c
 VP8_DX_SRCS-$(HAVE_ARMV6)  += decoder/arm/dsystemdependent.c
 VP8_DX_SRCS_REMOVE-$(HAVE_ARMV6)  += decoder/generic/dsystemdependent.c
+VP8_DX_SRCS_REMOVE-$(HAVE_ARMV6)  += decoder/dequantize.c
 VP8_DX_SRCS-$(CONFIG_ARM_ASM_DETOK)  += decoder/arm/detokenize$(ASM)
 
 #File list for armv6