ld --gc-sections failures

[Alan Modra]

I'm getting a ld testsuite failure for --target=i586-linux.  It's been
around for a while.

gcc -w -O2 -ffunction-sections -fdata-sections -fvtable-gc -fno-exceptions
-fno-rtti -B/usr/tmp/gas/ld/tmpdir/gas/ 
-I/usr/src/binutils-current/ld/testsuite/ld-selective -g -O2 -W -Wall  -c
/usr/src/binutils-current/ld/testsuite/ld-selective/3.cc -o tmpdir/3.o

/usr/tmp/gas/ld/ld-new  -o tmpdir/3.x --gc-sections -Bstatic tmpdir/3.o

/usr/tmp/gas/ld/../binutils/nm-new  tmpdir/3.x >tmpdir/nm.out

foo__1B == 0x08048090
FAIL: selective4

As far as I can see, tmpdir/3.o looks OK;  foo__1B is in it's own section
.text.foo__1B, and isn't referenced.  ld doesn't seem to want to do any
garbage collection.

I haven't spent any time trying to track this down, as I was hoping
someone would know what's going wrong off the top of their head.