darwin: do not use -mdynamic-no-pic

While -mdynamic-no-pic can speed up the code somewhat, it is only used
on the legacy PowerPC Mac OS X, and I am not sure if anyone is still
testing that.  Disabling PIC can cause problems when enabling modules,
so do not do that.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

configure

@@ -518,8 +518,6 @@ Darwin)
   if [ "$cpu" = "x86_64" ] ; then
     QEMU_CFLAGS="-arch x86_64 $QEMU_CFLAGS"
     LDFLAGS="-arch x86_64 $LDFLAGS"
-  else
-    QEMU_CFLAGS="-mdynamic-no-pic $QEMU_CFLAGS"
   fi
   cocoa="yes"
   audio_drv_list="coreaudio"