SVN r305382 breaks world32 on amd64 (and native 32-bit)

[Michael Butler]

Build fails with:

===> lib/msun (obj,all,install)
Building /usr/obj/usr/src/lib/msun/e_fmodf.o
/usr/src/lib/msun/i387/e_fmodf.S:10:17: error: register %rsp is only
available in 64-bit mode
 movss %xmm0,-4(%rsp)
                ^~~~
/usr/src/lib/msun/i387/e_fmodf.S:11:17: error: register %rsp is only
available in 64-bit mode
 movss %xmm1,-8(%rsp)
                ^~~~
/usr/src/lib/msun/i387/e_fmodf.S:12:10: error: register %rsp is only
available in 64-bit mode
 flds -8(%rsp)
         ^~~~
/usr/src/lib/msun/i387/e_fmodf.S:13:10: error: register %rsp is only
available in 64-bit mode
 flds -4(%rsp)
         ^~~~
/usr/src/lib/msun/i387/e_fmodf.S:18:11: error: register %rsp is only
available in 64-bit mode
 fstps -4(%rsp)
          ^~~~
/usr/src/lib/msun/i387/e_fmodf.S:19:11: error: register %rsp is only
available in 64-bit mode
 movss -4(%rsp),%xmm0
          ^~~~
*** Error code 1

Stop.
make[4]: stopped in /usr/src/lib/msun