library with a shared object dependency that contained alias symbols,
the linker incorrectly counted the number of symbols that would be
written, resulting in a fatal internal error. Since our libc now
contains some alias symbols (in "net/res_stubs.c"), this was
sufficient to tickle the bug: "ld -Bshareable foo.so -lc". To
fix it, I moved the accounting of alias symbols to a later point
in the processing, where it is possible to count only those symbols
that will actually be written to the output file.
This fix is well-confined to affect alias symbols only. I have
tested it with a full "make world". I am going to merge it into
-2.2 after a few more days of living with it in -current.
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