setup_once: use enum type for 'bool' on non-C99 platforms

An enum will catch non-bool assignments to bool on platforms with
a strict compiler, e.g MIPSPro.

Signed-off-by: Kamil Dudka <kdudka@redhat.com>

CHANGES

@@ -6,13 +6,17 @@
 
                                   Changelog
 
+Kamil Dudka (27 May 2010)
+- Tor Arntsen changed the alternative definition of bool to use enum instead
+  of unsigned char.
+
+Daniel Stenberg (25 May 2010)
 - Julien Chaffraix fixed the warning seen when compiling lib/rtmp.c: one
   unused variables, several unused arguments and some missing #include.
 
 - Julien Chaffraix fixed 2 OOM errors: a missing NULL-check in
   lib/http_negociate.c and a potential NULL dereferencing in lib/splay.c
 
-Daniel Stenberg (25 May 2010)
 - Howard Chu brought a patch that makes the LDAP code much cleaner, nicer and
   in general being a better libcurl citizen. If a new enough OpenLDAP version
   is detect, the new and shiny lib/openldap.c code is then used instead of the