abiversions not working correctly for ld.so on MIPS-Linux

[Roland McGrath]

The trouble here results from inconsistent treatment of ld.so vs lib*.so
in the Versions files and associated magic.  Arguably `ld {' should appear
in elf/Versions instead of `ld.so {' just as `libc {' appears instead
of `libc.so {'.  The soversions.i -> Versions.all processing doesn't make
ld.so any kind of special case, so the intermediate processing produces
a line "ld : GLIBC_2.0 GLIBC_2.2" instead of "ld.so : GLIBC_2.0 GLIBC_2.2",
which fails to match the "ld.so {" section.

I think the best solution would be to clean up all the magic so that it
expects to see "ld {" instead of "ld.so {", just like for every other *.so
there is (which all happen to be lib*.so).  I haven't looked into the
issues there might be with this.