EH frame optimization bug

[Daniel Jacobowitz]

Testcase derived from glibc.  Take the attached files and link them:
  ld -o bin connect.o send.o dumb.o

readelf -wf bin -> segfault.

The problem is that we've got GAS-produced .eh_frame sections that look like
this:
  [ 5] .eh_frame         PROGBITS        00000000 000098 000040 00   A  0  0  4

00000000 00000012 00000000 CIE

00000016 00000026 0000001a FDE cie=00000000 pc=0000001e..00000074

Then we have two almost identical object files (built from the same source
file, actually).  We optimize them to share a CIE.

00000000 00000012 00000000 CIE
00000016 00000026 0000001a FDE cie=00000000 pc=08048080..080480d6
00000040 00000026 00000044 FDE cie=00000000 pc=080480e0..08048136

That second FDE now ends at 0x6a.  The next .eh_frame section is align-4. 
Two bytes padding get added, and everything blows up.

Something similar came up a few months ago but I can't find the reference
now.  What's the right thing to do here?  My instinct says, grow the last
FDE before the padding, but I have no idea how to do that.  Is the alignment
of a .eh_frame section mandated?

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer