Add dependency to yasm on i386 and amd64 platform.
Fix build on i386 and amd64.
Thank you, wiz@.
Update to Chicken 4.8.0.1
Requested by Peter Bex.


Changes in 4.8.0.1 since 4.8.0

- Security fixes
  - Use POSIX poll() on systems where available.  This avoids a design flaw
    in select(); it supports no more than FD_SETSIZE descriptors.

- Core libraries
  - Fixed EINTR handling in process-wait and when reading from file ports.
  - Bugfix for irregex (#686).  Note: although irregex.scm now says version
    0.9.2, the version is actually 0.8.3 plus a few backported patches.
  - Fixed problem in "make-pathname" that returned an absolute path if given
    a relative one without a directory argument.
  - On 64-bit systems the feature identifier "64bit" is registered.

- Compiler
  - Fixed various bugs in the type database.
  - Bugfixes and improvements in the scrutinizer.
  - In the flow-analysis pass, type-matching of combinations of
    "list"/"list-of" types has been made more reliable.

- Syntax expander
  - Make macro-renamed defines in begin bodies (inside modules)
    visible to later forms. (#944).

- Runtime system
  - Fixed incorrect code in the foreign argument conversion for
    "unsigned-integer64" (#955).

- Core tools
  - The runtime linker path for compiled executables was not set correctly
    on FreeBSD systems.
  - Fix install-extension breakage when the second arg contains pairs (SRC DST).

- Build system
  - Prevent rebuilding of buildversion.scm on every make(1) on Windows.
Updated lang/chicken to 4.8.0.1