Fix forward transform compilation errors

BUG=aomedia:395

Change-Id: I381f16e66e2540c9bf24727abf8915a3850dcc92

aom_dsp/aom_dsp.mk

@@ -209,6 +209,8 @@ DSP_SRCS-$(HAVE_MSA)    += mips/txfm_macros_msa.h
 
 # forward transform
 ifneq ($(findstring yes,$(CONFIG_AV1)$(CONFIG_PVQ)),)
+DSP_SRCS-$(HAVE_AVX2)   += x86/txfm_common_avx2.h
+ifeq ($(CONFIG_AV1_ENCODER),yes)
 DSP_SRCS-yes            += fwd_txfm.c
 DSP_SRCS-yes            += fwd_txfm.h
 DSP_SRCS-$(HAVE_SSE2)   += x86/fwd_txfm_sse2.h
@@ -221,12 +223,12 @@ DSP_SRCS-$(HAVE_SSSE3)  += x86/fwd_txfm_ssse3_x86_64.asm
 endif
 DSP_SRCS-$(HAVE_AVX2)   += x86/fwd_txfm_avx2.h
 DSP_SRCS-$(HAVE_AVX2)   += x86/fwd_txfm_avx2.c
-DSP_SRCS-$(HAVE_AVX2)   += x86/txfm_common_avx2.h
 DSP_SRCS-$(HAVE_AVX2)   += x86/fwd_dct32x32_impl_avx2.h
 DSP_SRCS-$(HAVE_NEON)   += arm/fwd_txfm_neon.c
 DSP_SRCS-$(HAVE_MSA)    += mips/fwd_txfm_msa.h
 DSP_SRCS-$(HAVE_MSA)    += mips/fwd_txfm_msa.c
 DSP_SRCS-$(HAVE_MSA)    += mips/fwd_dct32x32_msa.c
+endif  # CONFIG_AV1_ENCODER
 endif  # CONFIG_AV1
 
 # inverse transform