Require armv6/media when building armv7

When building with runtime cpu detect assume that armv7 targets can be
relied upon to have at least armv6 support. This may allow dead code
detectors to remove some _c functions.

Change-Id: Iaec4414011fcbbdf6f4ed0d90ef4a8fe8af540b5

build/make/rtcd.pl

@@ -385,6 +385,8 @@ if ($opts{arch} eq 'x86') {
   arm;
 } elsif ($opts{arch} eq 'armv7') {
   @ALL_ARCHS = filter(qw/edsp media neon_asm neon/);
+  @REQUIRES = filter(keys %required ? keys %required : qw/media/);
+  &require(@REQUIRES);
   arm;
 } elsif ($opts{arch} eq 'armv8') {
   @ALL_ARCHS = filter(qw/neon/);