Fix missing headers with xiphrc and daala-dist

Fixed the build fail in the xiphrc and daala-dist, which are tested
for inclusion in libaom__compile_experiments but produced error
as reported in above bug report.

Thanks to James Zern for reporting and suggesting how to fix.

BUG=https://bugs.chromium.org/p/aomedia/issues/detail?id=370

Change-Id: I46823255012e6c3d20b57e3bd65a45c03de8222c
diff --git a/av1/av1_common.mk b/av1/av1_common.mk
index 02bd4a6..db5b2fd 100644
--- a/av1/av1_common.mk
+++ b/av1/av1_common.mk
@@ -115,15 +115,15 @@
 AV1_COMMON_SRCS-yes += common/zigzag32.c
 AV1_COMMON_SRCS-yes += common/zigzag.h
 AV1_COMMON_SRCS-yes += common/generic_code.c
-AV1_COMMON_SRCS-yes += common/generic_code.h
 AV1_COMMON_SRCS-yes += common/pvq_state.c
-AV1_COMMON_SRCS-yes += common/pvq_state.h
 AV1_COMMON_SRCS-yes += common/laplace_tables.c
 AV1_COMMON_SRCS-$(HAVE_SSE4_1) += common/x86/pvq_sse4.c
 AV1_COMMON_SRCS-$(HAVE_SSE4_1) += common/x86/pvq_sse4.h
 endif
-ifneq ($(findstring yes,$(CONFIG_PVQ)$(CONFIG_DAALA_DIST)),)
+ifneq ($(findstring yes,$(CONFIG_PVQ)$(CONFIG_DAALA_DIST)$(CONFIG_XIPHRC)),)
 AV1_COMMON_SRCS-yes += common/pvq.h
+AV1_COMMON_SRCS-yes += common/pvq_state.h
+AV1_COMMON_SRCS-yes += common/generic_code.h
 endif
 
 ifneq ($(CONFIG_AOM_HIGHBITDEPTH),yes)