Fix finite*() definitions in include/api/math.h

include/api/math.h included wrong declaration for finitef(), finite()
and finitel() - these should always return int (basically, a boolean),
*not* a floating-point number.

Probably before commit 4e8076829f3e8126b967f1d5b51c10b02ff290ba removed
the duplicate math.h, this didn't matter. But now it matters and
compilation fails because of the declaration is inconsistent with the
actual definition.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
libc: add include path for locale

Signed-off-by: Takuya ASADA <syuu@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>