FreeBSD_HEAD_amd64_gcc4.9 - Build #668 - Fixed

FreeBSD_HEAD_amd64_gcc4.9 - Build #668 - Fixed:

Build information: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/668/
Full change log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/668/changes
Full build log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/668/console

Change summaries:

289415 by mav:
Bump version and add notice about incompatibility introduced by resumable
send/receive support in ZFS.

289411 by bdrewery:
Tweak the default target to not suggest 'all' since it really doesn't do
anything useful for most users.

MFC after:	2 weeks
Sponsored by:	EMC / Isilon Storage Division

289410 by bdrewery:
Avoid warning race with creating 'ldscripts' directory during build.

In r204548 the 'rm -f ldscripts' was added likely due to reading the
conditional as 'else it is a file'.  That seems unlikely though and
the more likely case is just that the directory hasn't been created yet.

Because this races with ,ssother scripts, use 'mkdir -p' which is a minimal
modification vs upstream to avoid the warning of 'File exists' if another
script creates it first.  This could replace the 'test -d' as well but
then it's more unneeded change to the upstream script.

Sponsored by:	EMC / Isilon Storage Division

289409 by bdrewery:
Add entries for moved test symbols for r289355 and r289330.

This list is likely not complete.

Sponsored by:	EMC / Isilon Storage Division

289408 by bdrewery:
Similar to r289355, /usr/tests is within the base system so put the symbols
into /usr/lib/debug.

This covers some missing files:
  /usr/tests/libexec/rtld-elf/.debug
  /usr/tests/libexec/rtld-elf/.debug/libpythagoras.so.0.debug
  /usr/tests/lib/libc/tls/.debug
  /usr/tests/lib/libc/tls/.debug/libh_tls_dynamic.so.1.debug
  /usr/tests/lib/libc/tls/.debug/h_tls_dlopen.so.debug
  /usr/tests/lib/libthr/dlopen/.debug
  /usr/tests/lib/libthr/dlopen/.debug/h_pthread_dlopen.so.1.debug
  /usr/tests/lib/libxo/.debug
  /usr/tests/lib/libxo/.debug/libenc_test.so.debug

Sponsored by:	EMC / Isilon Storage Division

289407 by bdrewery:
Fix delete-old and check-old-files not removing old debug symbols.

This was handled for libraries in r256842 but for some reason was missed
for files (bsd.prog.mk).

MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division
Relnotes:	yes

289405 by imp:
Do not relocate extents to make them contiguous if the underlying drive can do
deletions. Ability to do deletions is a strong indication that this
optimization will not help performance. It will only generate extra write
traffic. These devices are typically flash based and have a limited number of
write cycles. In addition, making the file contiguous in LBA space doesn't
improve the access times from flash devices because they have no seek time.

Reviewed by: mckusick_at_