ld: microblaze: ignore rwx segments

The linker will generate warnings if it is creating an executable
stack or a segment with all three read, write and execute permissions.
These settings are not appropriate for all targets including
MicroBlaze.

Signed-off-by: Neal Frager <neal.frager@amd.com>
Signed-off-by: Michael J. Eager <eager@eagercon.com>

ld/configure.tgt

@@ -55,6 +55,7 @@ if test "${ac_default_ld_warn_rwx_segments}" = unset; then
     cris-*-* | crisv32-*-* | \
     hppa*-*-* | \
     mips*-*-* | \
+    microblaze*-*-* | \
     sparc*-*-* | \
     v850*-*-*)
       ac_default_ld_warn_rwx_segments=0