config.gcc (all gnu and linux): Use t-slibgcc-elf-ver with t-linux.
* config.gcc (all gnu and linux): Use t-slibgcc-elf-ver with t-linux.
(i386-*-solaris2): Use t-slibgcc-elf-ver or t-slibgcc-sld.
(sparc*-*-solaris2): Likewise.
* config/t-linux: Remove shared libgcc macros.
* config/t-slibgcc-elf-ver: Move from sparc/t-slibgcc.
* config/t-slibgcc-sld: Move from sparc/t-slibgcc-sld.