sp_lev.c warnings

sp_lev.c warnings

Fix a couple of warnings about prototype not matching function definition.
Prototype specified a narrow scalar ('boolean') but function uses old-style
definition which implicitly promotes narrow types (char,short,'boolean' to
int, float to double).  Switch prototypes to BOOLEAN_P.

A whole bunch of prototypes specify STATIC_DCL ('static') and then leave
the definition without STATIC_OVL (also 'static').  I only fixed up a
couple of those, but we risk getting somebody using an old compiler that
doesn't like
  static int foo();
  int foo() { return 42; }
Even if every comiler accepts that (I don't recall whether that was kosher
in the ancient K&R days), you can't tell by looking at the function
defintion (in the usual case where the forward declarations are at the top
of the file rather than immediately before the defintiion) whether it's
local to that file or global, so the missing STATIC_OVL qualifiers ought
to be added.