Choose the input source file encoding in a locale-independent way.

Choose the input source file encoding in a locale-independent way.

This is so that compiling the same code on environments with different
locale settings yields the same result.

* module/system/base/compile.scm (compile-file): When ENC if #f, default
  to "UTF-8" instead of `(fluid-ref %default-port-encoding)'.

* doc/ref/api-evaluation.texi (Compilation): Document the default output
  file name and default source file encoding for `compile-file' and
  `guile-tools compile'.