Fix compilation with solaris 11

Based on original patch from Nathan Tamblyn.

Fix #831

core/hooks.c

@@ -396,9 +396,10 @@ static int uwsgi_hook_chown2(char *arg) {
 }
 
 
-#ifdef __sun__
+#if defined(UWSGI_SUNOS_EXTERN_SETHOSTNAME)
 extern int sethostname(char *, int);
 #endif
+
 static int uwsgi_hook_hostname(char *arg) {
 #ifdef __CYGWIN__
 	return -1;

uwsgiconfig.py

@@ -810,7 +810,12 @@ class uConf(object):
             self.libs.append('-lsendfile')
             self.libs.append('-lrt')
             self.gcc_list.append('lib/sun_fixes')
-            self.ldflags.append('-L/lib')
+            sunos_major = int(uwsgi_os_k.split('.')[0])
+            sunos_minor = int(uwsgi_os_k.split('.')[1])
+            # solaris < 11 does not have sethostname declared in unistd
+            if not (sunos_major == 5 and sunos_minor > 10):
+                self.cflags.append('-DUWSGI_SUNOS_EXTERN_SETHOSTNAME')
+                self.ldflags.append('-L/lib')
             if not uwsgi_os_v.startswith('Nexenta'):
                 self.libs.remove('-rdynamic')