deinterlace: use VLC_ALTIVEC

(cherry picked from commit 04cfde414e)

configure.ac

@@ -1612,7 +1612,6 @@ AS_IF([test "${enable_altivec}" = "yes"], [
   AS_IF([test "${ac_cv_c_altivec}" != "no"], [
     CPPFLAGS="${CPPFLAGS} ${ac_cv_c_altivec}"
     AC_DEFINE(CAN_COMPILE_C_ALTIVEC, 1, [Define to 1 if C AltiVec extensions are available.])
-    VLC_ADD_CFLAGS([deinterlace],[${ac_cv_c_altivec}])
     have_altivec="yes"
   ])
   AC_CHECK_HEADERS(altivec.h)

modules/video_filter/deinterlace/merge.c

@@ -179,6 +179,7 @@ void Merge16BitSSE2( void *_p_dest, const void *_p_s1, const void *_p_s2,
 #endif
 
 #ifdef CAN_COMPILE_C_ALTIVEC
+VLC_ALTIVEC
 void MergeAltivec( void *_p_dest, const void *_p_s1,
                    const void *_p_s2, size_t i_bytes )
 {