Necessary support for Gcc 4.6+

[schapman30]

My build that has worked on older versions of RHEL running with older versions of GCC is now failing and producing the error "gcc: error: unrecognized command line option '--whole-archive'" because gcc 4.8 is treating the "--whole-archive" flag as a compiler option. It is now necessary to include "-Wl" before linker options. This is not currently supported with this plugin; it should be updated to prepend "-Wl" to linker flags.

From 4.6 release notes: "GCC now has stricter checks for invalid command-line options. In particular, when gcc was called to link object files rather than compile source code, it would previously accept and ignore all options starting with --, including linker options such as --as-needed and --export-dynamic, although such options would result in errors if any source code was compiled. Such options, if unknown to the compiler, are now rejected in all cases; if the intent was to pass them to the linker, options such as -Wl,--as-needed should be used." https://gcc.gnu.org/gcc-4.6/changes.html