Revert "Remove unused 3dnow and mmxext checks"

This reverts commit 6fe7eb60.
These checks are still in use outside of memcpy() optimizations.
Note this revert breaks the build on some platforms due to code rot.

configure.ac

@@ -1095,6 +1095,7 @@ AC_ARG_ENABLE(mmx,
   esac
 ])
 have_mmx="no"
+have_mmxext="no"
 AS_IF([test "${enable_mmx}" != "no"], [
   ARCH="${ARCH} mmx"
   VLC_SAVE_FLAGS
@@ -1141,9 +1142,26 @@ asm volatile("packuswb %%mm1,%%mm2"::"r"(p):"mm1", "mm2");
     have_mmx="yes"
   ])
 
+  AC_CACHE_CHECK([if $CC groks MMX EXT inline assembly],
+                 [ac_cv_mmxext_inline], [
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,[[
+void *p;
+asm volatile("maskmovq %%mm1,%%mm2"::"r"(p):"mm1", "mm2");
+]])
+    ], [
+      ac_cv_mmxext_inline=yes
+    ], [
+      ac_cv_mmxext_inline=no
+    ])
+  ])
   VLC_RESTORE_FLAGS
+  AS_IF([test "${ac_cv_mmxext_inline}" != "no"], [
+    AC_DEFINE(CAN_COMPILE_MMXEXT, 1, [Define to 1 if MMX EXT inline assembly is available.])
+    have_mmxext="yes"
+  ])
 ])
 AM_CONDITIONAL([HAVE_MMX], [test "${have_mmx}" = "yes"])
+AM_CONDITIONAL([HAVE_MMXEXT], [test "${have_mmxext}" = "yes"])
 
 dnl  Check for fully workin SSE2 intrinsics
 dnl  We need support for -mmmx, we need <emmintrin.h>, and we also need a
@@ -1307,6 +1325,29 @@ asm volatile("insertq %%xmm1,%%xmm0"::"r"(p):"xmm0", "xmm1");
 ])
 AM_CONDITIONAL([HAVE_SSE2], [test "$have_sse2" = "yes"])
 
+VLC_SAVE_FLAGS
+CFLAGS="${CFLAGS} -mmmx"
+have_3dnow="no"
+AC_CACHE_CHECK([if $CC groks 3D Now! inline assembly], [ac_cv_3dnow_inline], [
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,[[
+void *p;
+asm volatile("pfadd %%mm1,%%mm2"::"r"(p):"mm1", "mm2");
+]])
+  ], [
+    ac_cv_3dnow_inline=yes
+  ], [
+    ac_cv_3dnow_inline=no
+  ])
+])
+VLC_RESTORE_FLAGS
+AS_IF([test "${ac_cv_3dnow_inline}" != "no"], [
+  AC_DEFINE(CAN_COMPILE_3DNOW, 1,
+            [Define to 1 if 3D Now! inline assembly is available.])
+  have_3dnow="yes"
+])
+AM_CONDITIONAL([HAVE_3DNOW], [test "$have_3dnow" = "yes"])
+
+
 AC_ARG_ENABLE(neon,
   [AS_HELP_STRING([--disable-neon],
     [disable NEON optimizations (default auto)])],, [