Windows .FASL extension should force LOAD to treat as fasl file
This is about how SBCL deals with invalid fasl files, like fasl files from other implementations.
On Windows, (load "foo.fasl") will load the file as fasl file, and signal FASL-HEADER-MISSING if the header is invalid. OK.
But loading the same file as (load "foo.FASL") will treat invalid an fasl as source code, which leads to somewhat strange errors (e.g. UNBOUND-VARIABLE of a variable whose name contains unprintable bytes).
As nobody would give a source file the extension FASL, I propose that the test for the "fasl" extension is done on Windows with string-equals instead of string= (function load, in src/code/