* config.gcc (*-*-freebsd*): Enable creation of libgcc_s.so.
	* config/t-slibgcc-elf-ver (SHLIB_LC): Add macro and use it.
	No functional change except ...
	* config/t-slibgcc-nolc-override (SHLIB_LC): Override it.  New file.
	* doc/install.texi (*-*-freebsd*): Document port configuration.

From-SVN: r51574