Copied from Debian.

From: Rodeo
Origin: https://github.com/HandBrake/HandBrake/blob/master/contrib/a52dec/A04-modern-gcc-cflags.patch

--- a52dec-0.7.4/configure.in.orig
+++ a52dec-0.7.4/configure.in
@@ -34,11 +34,11 @@
     case "$host" in
     i?86-* | k?-*)
 	case "$host" in
-	i386-*) OPT_CFLAGS="$CFLAGS -mcpu=i386";;
-	i486-*) OPT_CFLAGS="$CFLAGS -mcpu=i486";;
-	i586-*) OPT_CFLAGS="$CFLAGS -mcpu=pentium";;
-	i686-*) OPT_CFLAGS="$CFLAGS -mcpu=pentiumpro";;
-	k6-*)   OPT_CFLAGS="$CFLAGS -mcpu=k6";;
+	i386-*) OPT_CFLAGS="$CFLAGS -mtune=i386";;
+	i486-*) OPT_CFLAGS="$CFLAGS -mtune=i486";;
+	i586-*) OPT_CFLAGS="$CFLAGS -mtune=pentium";;
+	i686-*) OPT_CFLAGS="$CFLAGS -mtune=pentiumpro";;
+	k6-*)   OPT_CFLAGS="$CFLAGS -mtune=k6";;
 	esac
 	AC_TRY_CFLAGS([$OPT_CFLAGS],[CFLAGS=$OPT_CFLAGS]);;
     sparc-* | sparc64-*)