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
(cherry picked from commit 5a566771e089d5ff5c7881080cd2e0e73a61b5da)
JIT: fix inlined `char->integer' and `integer->char'

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

Merge to v5.3.4
(cherry picked from commit 0c4e155b88288191d1e6d969afa5e78020150ca8)
merge history for v5.3.4

Merge to v5.3.4
(based on 9b7e3be)
Update TR history for 5.3.4.
(cherry picked from commit 85eab5610f53450a2365e1967ba1c84927599772)
Corrected a variety of wrong-arg-type error messages for map-image,
build-image, et al.

Please merge to release branch.
(cherry picked from commit 6740ab5748a9ae0997700b22f8c3c46ed6fa0f1b)