FAIL: Link -r with zlib compressed debug output

[Alan Modra]

HJ, this test is failing on ppc64 with gcc5 due to the size of
.debug_info simply being too small to show any benefit of compression.

(gdb) set args -I /src/binutils-gdb/ld/testsuite/ld-elf -a64 -mppc64 -many -mbig --compress-debug-sections=zlib -o tmpdir/begin.o begin.s
Breakpoint 9 at 0x1002eda0: file /src/binutils-gdb/gas/write.c, line 1537.
(gdb) r
Starting program: /home/alan/build/ppc/bin/gas/as-new -I /src/binutils-gdb/ld/testsuite/ld-elf -a64 -mppc64 -many -mbig --compress-debug-sections=zlib -o tmpdir/begin.o begin.s

Breakpoint 9, compress_debug (abfd=0x101b11c0, sec=0x101c7e90, xxx=<optimized out>) at /src/binutils-gdb/gas/write.c:1537
1537	  if (compressed_size >= uncompressed_size)
(gdb) p compressed_size
$1 = 82
(gdb) p uncompressed_size
$2 = 82
(gdb) 

On x86_64 the numbers are 80/82, so even on x86 you're only just
squeaking in a pass.  Can you look at using a larger source file for
this test, to make it more robust?

-- 
Alan Modra
Australia Development Lab, IBM