complibs/ppl: update GMP location configuration argument for PPL v0.11 and later

'configure' for PPL 0.11 (and later) needs "--with-gmp-prefix" to
provide the location of the GMP toolkit; the previous switches were
"--with-libgmp-prefix" and "--with-libgmpxx-prefix".

The upstream log message is:

commit 08dfb6fea094f8c5a533575a3ea2095edce99a6d
Author: Roberto Bagnara <bagnara@cs.unipr.it>
Date: Sun Jul 12 21:39:46 2009 +0200

New configure option --with-gmp-prefix supersedes the (now removed)
options --with-libgmp-prefix and --with-libgmpxx-prefix.

Link: http://www.cs.unipr.it/git/gitweb.cgi?p=ppl/ppl.git;a=commit;h=08dfb6fea094f8c5a533575a3ea2095edce99a6d

Since PPL's 'configure' ignores unknown switches, we use all three so we
don't have to conditionalize the ppl.sh build script itself.

Signed-Off-By: Anthony Foiani <anthony.foiani@gmail.com>
(transplanted from 4f0c4fb572e2862c24b28e8d27ce7e9cb9adba65)

# powerpc specific configuration file

config ARCH_POWERPC_SPE

    bool

    prompt "Enable SPE support"

    default n

    help

      Add support for the Signal Processing Engine.  This will set up

      the toolchain so that it supports the SPE ABI extensions. This

      mainly targets Freescale e500 processors.

      Setting this option will append "spe" to the end of your target

      tuple name (e.g., powerpc-e500v2-linux-gnuspe) so that the gcc

      configure/build system will know to include SPE ABI support.

      It will also automatically add "-mabi=spe -mspe" to your

      TARGET_CFLAGS, and "--enable-e500_double" to your CC_EXTRA_CONFIG,

      so you do not need to explicitly add them.