Fix JIT for ARMv6 (i.e., no thumb support)
ARM JIT: use static configuration

The output of "/proc/cpuinfo" seems wrong for a Raspberry Pi running
the latest Raspian, because it claims ARMv6-compatible but also claims
"thumb" as a feature and 7 as the CPU architecture. Use the C compiler's
configuraton, instead, which is relatively straightforward and drops
code that will turn out to be dead.
Change the default stack size to safe values on OpenBSD.

With this patch racket will never grow beyond of the defaults limits of
the OS and also it doesn't limit the stack size to a fixed value.

Merge to v5.3.4
Unix: initialize `current-directory' from the PWD environment variables

... when PWD is defined and when it refers to the same directory
as the result of getcwd().

A shell sets PWD before starting Racket to communicate a preferred
way of referring to the current directory, which may involve soft
links that are not reflected in getpwd().
racket/system: make `system', etc., set PWD by default

That is, make `system' behave like a shell.
JIT: fix inlined `char->integer' and `integer->char'

Put the result in the destination register, instead of always R0.

Merge to v5.3.4
merge history for v5.3.4

Merge to v5.3.4
Update TR history for 5.3.4.
Corrected a variety of wrong-arg-type error messages for map-image,
build-image, et al.

Please merge to release branch.
Merge branch 'master' of pltgit:plt
I'm not sure why this is non-fast-forwardable, but it apparently is.
configure: strip debug symbols on install by default
src/README: improve notes on cross-compilation
android: disable libunwind for now

There's an issue with dl_iterate_phdr().
JIT ARM: improve stack trace

Fix a problem at the boundary of DWARF-driven backtrace
and frame-driver backtrace, as well as handling of the
JIT's different internal calling conventions.

Also, allow crossing back from frame-driven to DWARF-driven.
Add MZ_TRY_EXTFLONUMS to OpenBSD.

Also add an error to unsupported platforms (copied from FreeBSD).

Merge to 5.3.4
Fix types of `system` etc for new keyword arguments.

This requires extending the ->optkey type constructor to support rest
arguments, and fixing the keyword function type generation code.

Testing is still limited because there's no parsing for such types.
That will be handled in a later commit.
ffi/unsafe/obj: add `+A' and `-A' method modes

On Cocoa, a view's `drawRect:' method can be called from a
heartbeat thread that animates controls. Such a call happens
rarely for a `canvas%' or other class where `drawRect:'
is overridden, but since it can happen, ensure that the
callback runs on the Racket thread.
Complain visibly when cannot load GL shared libs, instead of swallowing error.
ffi/unsafe: add `_double' and `_float' tests
upgrade libffi to 3.0.13

This upgrade is particularly for repairs to ARM and the VFP ABI.