tests: Use cc by default, not gcc.
Fix undefined-function error not working on #-sb-dynamic-core.

When compiled with clang on FreeBSD the code which looks for
undefined_tramp's location goes through dlsym, but clang doesn't
export runtime symbols by default.
Go through dlsym only when sb-dynamic-core is actually enabled.
Make sb-dynamic-core work on FreeBSD.
Fix small bug in FUNCTION-LAMBDA-EXPRESSION
Config.x86-64-linux => Config.x86_64-linux.

Everything else uses a dash.
Use openpty() for run-program on FreeBSD.

Opening /dev/ptmx doesn't work for me on the default installation.
Workaround a problem in building SBCL under ABCL.

This issue is logged as http://abcl.org/trac/ticket/351
Fix build of new SYMBOL-INFO magic on targets without compare-and-swap-vops.

  * The (non-atomic) fallback position for compare-and-swap
requires some way to set the target value, which can be provided
as an explicit function name or will default to a SETF function.

  * Define (SETF SYMBOL-INFO) as a :SET-TRANS for the SYMBOL-INFO
slot and provide an interpreter stub for it.
Clean up some detritus from globaldb