- Build wasn't properly using -soname linker args, so installed libraries
could depend on relative paths from the build directory.
- Consolidated GNU linker args to one place in the BlueGeneP-base platform
file, since ld is used by both XL and GNU toolchains on BlueGene.
BlueGeneP-base: Internal base shared by static and dynamic files
BlueGeneP-static: Platform file for all-static builds
BlueGeneP-dynamic: Platform file for "default" dynamic builds