Adds libparrot_helper support for 32 and 64 bits.

When LD_PRELOAD contains the token '/$LIB/', this token is substituted by 'lib'
for 32-bit and 'lib64' for 64-bit. This commit tries to compile both the 32 and
64 bit versions of the helper, and installs them respectively in
lib/lib/libparrot_helper.so and lib/lib64/libparrot_helper.so, with
lib/libparrot_helper.so being the default architecture. This allows to write
something like:

setenv PARROT_HELPER '/path/to/cctools/lib/$LIB/libparrot_helper.so'

The single quotes are important, otherwise $LIB gets the value from the shell,
rather than from ld.

(I tested this on a fresh install of SL5.5. For the 32-bit version we seem to
be missing the i386 dev package in our installation of redhat5.5.)

Conflicts:

	parrot/src/Makefile