A bs_start_match2/5 instruction will never fail (take the branch) if
given a match state or a binary. Therefore, the type at the failure
label should be 'term', not match state or binary. Without this
correction, the beam_validator will reject safe programs.

To facilitate debugging of compiler bugs, teach the compiler the
'no_dead' option. Since the beam_dead pass used to do the necessary
splitting of basic blocks to expose all labels, we must move that
splitting into a separate pass that is always run.

Mark math:pi/0 as pure, informing the compiler that the value
can be calculated at compile time.

* bjorn/compiler/options/OTP-9752:
  filename documentation: Recommend against using filename:find_src/1,2
  Teach filename:find_src/1,2 to handle slim or stripped BEAM files
  filename: Eliminate failing call to Mod:module_info(source_file)
  filename.erl:filter_options/1: Remove handling of dead options
  compiler: Don't include {cwd,_} in module_info(compile)
  compiler: Don't include source code options in module_info(compile)
  hipe: Teach hipe to handle slim or stripped BEAM files

* bjorn/major-release-cleanups:
  observer tests: Test compatibility with R13, not R12
  emulator tests: Test compatibility with R13, not R12
  Teach the compiler the 'r14' option
  erl_lint: The types introduced in R12B-5 are no longer "newly introduced"
  otp_internal: Stop warning for functions removed in R12 or earlier

Conflicts:
	lib/stdlib/src/otp_internal.erl

The {cwd,Dir} option is always included if the module has been
compiled by erlc. Since its presence cannot be relied upon and it
wastes memory, get rid of it.

As far as I know, the purpose of the compiler options included in
Mod:module_info(compile) has never been documented.

An educated guess is that they are there in case you want to
re-compile the module with the same options, and also to aid in
debugging when you need to know how a module was compiled.

In neither case is there any need to include options given in the
source itself in options included in Mod:module_info(compile).
Including those options will only waste memory.

Therefore, only include in the BEAM file the options that were
given to compile:file/2.

Starting in ff432e262e65243cbc983fcb002527f8fae8c78b, sys_pre_expand
passes external funs through to the downstream passes. It used to
translate external funs to a call to erlang:make_fun/3. Therefore, we
will now need to handle external funs in sys_expand_pmod.

Noticed-by: Stavros Aronis