Update INSTALL.md with Xenial instructions

The buildbot is now building nightly ubuntu 16.04 packages. Include the steps to install.

Let bcc debian build depend on 3.7|3.8

In Xenial, llvm 3.8 will be available upstream without manual apt steps.
Add those packages as a possible dependency in our build.

Don't require "OS ABI" specification in libraries

lua: Properly support high-range 64 addresses

Install all required packages on ubuntu

The most important system libraries are listed like this by ldconfig:

	libc.so.6 (libc6,x86-64, OS ABI: Linux 3.0.0) => /lib64/libc.so.6

But most user-level libraries don't have the "OS ABI" and will not be
found by the regular expression.

	libz.so (libc6,x86-64) => /usr/lib64/libz.so

This makes the regular expression more permissive, so that it finds
those libraries as well.

Lua's native Number type is a 64-bit double with 52-bit precision, which
was causing rounding errors when storing and working with high-range
memory addresses (namely, addresses from the kernel, which are all in
the `0xffffffff........` range).

To work around this, we've made sure to never call `tonumber` on any
variables that represent memory addresses, and instead continue
operating on them with their native types: LuaJIT can work with the
underlying `uint64_t` type for these values and transparently perform
all kinds of numeric operations.

The only limitation of working with native 64-bit types in LuaJIT is
that they cannot be printed with the language's default `string.format`
API. To give better UX to probe writers, these APIs have been
monkeypatched so the `%p` format specifier will now properly handle
64-bit addresses and print them in an appropriate format.

bcc-lua: build bcc.lua and bcc.o in the build tree

miscellaneous cleanups to C++ and tools/trace

I didn't actually track this one down, but was getting some errors
coming out of kernel header files when perf_events.h was included first.
Move it after some std headers that mask the issue.

BPF programs aren't allowed to attach to these functions since deadlocks
may occur, thus the test would fail since no stack is collected. Use
update_elem to test instead.

The way to do exception printing in python2/3 compatible way is using
sys.exc_info()[0/1].

bcc-lua: switch to quiet by default

use --verbose to turn verbose output
Signed-off-by: Alexei Starovoitov <ast@fb.com>

Fixed tcpv4connect.py broken link on README

Fix for find_symbol method, issue #478

Add support for nixos

Add support for systems using a non-default ("/lib/modules") kernel lib
directory.

migrated gethostlatency to use bpf_perf_event

Standalone Lua tracing tool