nettle compilation issues on ppc64

[Cameron Berkenpas]

The latest security/nettle port (3.7.2_1) has issues compiling on ppc64. 
Looking at this asm file, I suspect it's auto generated. Here's the 
relevant snippet from the build failure:

cc: warning: argument unused during compilation: '-MP' 
[-Wunused-command-line-argument]
cc: warning: argument unused during compilation: '-MF 
aes-decrypt-internal-2.o.d' [-Wunused-command-line-argument]
aes-decrypt-internal-2.s:349:1: error: unexpected token at start of 
statement
.0:
^
aes-encrypt-internal-2.s:326:1: error: unexpected token at start of 
statement
.0:
^
rm -f libhogweed.a