Revert "SDT: Use %foo for section types rather than "foo""

This reverts commit a31190f59188830b78dce26f0fbc42084f27c3c1.

We broke glibc's build on rawhide due to the way they use SDT_PROBE_ASM.
There's really no way to correctly use %note in that scenario, where we
can't know if there's operand parsing or not.
testsuite: make sdt_asm.exp actually clean up
testsuite: New sdt_casm for STAP_PROBE_ASM

An attempted fix for PR13974 had broken STAP_PROBE_ASM, because in that
case there's some ambiguity whether %note and %progbits should be
%%-escaped.  We can't determine that in general, because it depends on
whether the user's asm() has operands.  That fix was thus reverted, and
we're testing to make sure STAP_PROBE_ASM doesn't regress again.
Make systemtap.examples/io/deviceseeks.stp work on older kernels.

* testsuite/systemtap.examples/io/deviceseeks.stp: Handle older kernel's
  names for the sector size field.
Basic SystemTap support for aarch64

The SystemTap runtime libraries needs a number of machine specific
details for each architecture to be specified.  This is an attempt to
provide the minimal set of them so that a "hello, world" SystemTap
script will compile.
stap-report: add kernel compiler version
PR15123: when PR15123_ASSUME_MFENTRY is set, don't check for -mfentry flag

-mfentry flag is recorded in `DW_AT_producer` only if
`CFLAGS=-grecord-gcc-switches` was used at compilation-time. We
provide PR15123_ASSUME_MFENTRY as an environment variable to override
this detection. The user is expected to set this variable only if it
is confident that that CFLAGS=-mfentry was used.
Fix PR15982 by making 'process.end' probes work reliably.

* runtime/linux/task_finder.c: Swith from using UTRACE_DEATH events to
  using UTRACE_EXIT events, to avoid missing 'process.end' probes.
* tapset-utrace.cxx (utrace_derived_probe_group::emit_linux_probe_decl):
  For CONFIG_UTRACE, use UTRACE_EXIT events instead of UTRACE_DEATH
  events.
* testsuite/systemtap.base/proc_exec.exp: Tweak expected output.
Add a NEWS item about the PR15982 fix.
Revert tapset/s390/registers.stp commit.

* tapset/s390/registers.stp: Revert inadvertent commit d063c0e.
Fix minor errors found by clang analyzer

* dwflpp.cxx (dwflpp::iterate_over_plt): A bad plt_shdr pointer could be
  dereferenced later in the function.
* mdfour.c (m): This static global pointer was retaining stack memory.
  It's not needed at all - just pass an additional parameter as needed.
* stapregex-tree.cxx (range_union): In a twisted situation where old_b
  is NULL, and old_a is valid but empty, then old_b was dereferenced.
  This logic now stops trying to shortcut the empty case.  Also, the
  segment merging now uses std::merge, instead of doing it manually.
* staprun/stap_merge.c (main): Initialize num[];
* tapset-been.cxx (be_builder::build): Simplify 'priority' init;
* tapsets.cxx (dwarf_builder::build): Assert dw is always set.
* util.cxx (stap_spawn): Don't leave an unused 'cmd' local when SDT is
  not enabled.
nothing ever changes
stap-report: also include $HOME/.systemtap/rc
PR9822: reduce timer load

Until this very moment, runtime/time.c's tsc-polling timer (the one
related to __stp_time_timer_callback) was being invoked every jiffy,
ie. something like 1000Hz, just to tune our per-cpu estimates of
tsc/real-time.  This is excessive.  Instead, use a much longer
interval (10Hz), and an even larger yet if cpufreq-change-notification
is in effect (0.1Hz).

* runtime/time.c (STP_TIME_SYNC_INTERVAL): New overrideable macro.
  (__stp_init_time, __stp_time_timer_callback): Use it.
  (__stp_time_cpufreq_callback): Refresh base_ns/base_cycles.
RHBZ1012133: tweak periodic.stp demo to operate without kernel-debuginfo
eventcount sample: add -G lines=NNN option

So now 'stap eventcount.stp -G lines=15 -G sort=count PROBEPOINT'
is a nice enjoyable report. without excessive screen scrollage.
i18n: update-po
Add a top-level examples symlink into the testsuite
man/stap.1: small correction

This correction might be useful for those who want to parse the output.
Also add a small comment in stapsh.c to clarify the STAPSH_MAX_ARGS
comparison.
stapsh-unix.exp: give time for socat to get set up

I've observed a few failures of this test in which stap gives the "No
such file or directory" error on connect() even though socat was started
properly. This happens the first time the test is run, but not
subsequent times. My theory is that socat takes some time to be loaded
and set up on the first run.

Looking at past testsuite results seem to indicate that this test failed
frequently, so this may have been a long-standing issue. Either way,
this small wait seems to do the trick.