configure binutils with --enable-shared

[mwolfram@…]

MacPorts: 1.8.1 binutils: 2.20

Currently binutils will build a libbfd which requires one to link against libiberty.a. When one creates a shared library which uses libbfd this fails because the libiberty.a has a dependency on _environ which is only linked to executables.

configuring binutils with --enable-shared will place libiberty code into libbfd and libopcodes and enables building of other shared libraries using libbfd.

So it would be great to have binutils install the shared version by default.

[jmr@…]

r60374

[ryandesign@…]

Increased revision in r60739 so everyone gets the change.

Following r60374, the .la files now have sections like these, when building with the universal variant:

# Libraries that this one depends upon.
#ifndef __LP64__
dependency_libs=' -L/opt/local/lib -L/opt/local/var/macports/build/_Users_rschmidt_macports_dports_devel_binutils/work/binutils-2.20-i386/opcodes/../libiberty/pic -liberty'
#else /* __LP64__ */
dependency_libs=' -L/opt/local/lib -L/opt/local/var/macports/build/_Users_rschmidt_macports_dports_devel_binutils/work/binutils-2.20-x86_64/opcodes/../libiberty/pic -liberty'
#endif /* __LP64__ */

I assume these files are therefore now unusable, since I don't think C preprocessor directives are legal in .la files. I've added a comment about this to #21953.