log: Don't modify global @errno in __print_on_level

The __print_on_level routine may modify global @errno
variable which is inacceptable: this is logging routine
which must be transparent to the rest of the program code.

Thus save @errno in local @__errno variable and restore
it on return.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

log.c

@@ -155,6 +155,7 @@ unsigned int log_get_loglevel(void)
 static void __print_on_level(unsigned int loglevel, const char *format, va_list params)
 {
 	int fd, size, ret, off = 0;
+	int __errno = errno;
 
 	if (unlikely(loglevel == LOG_MSG)) {
 		fd = STDOUT_FILENO;
@@ -176,6 +177,7 @@ static void __print_on_level(unsigned int loglevel, const char *format, va_list
 			break;
 		off += ret;
 	}
+	errno =  __errno;
 }
 
 void print_on_level(unsigned int loglevel, const char *format, ...)