Bump cloudlibc to version 0.99.

This release adds pthread_cond_timedwait_relative_np(). As support for
this has also been added to CloudABI itself, this function may make some
functions that do relative waits more efficient.

Author: EdSchouten

src/include/_/cdefs.h

@@ -27,7 +27,7 @@
 // Version information.
 #define __cloudlibc__ 1
 #define __cloudlibc_major__ 0
-#define __cloudlibc_minor__ 98
+#define __cloudlibc_minor__ 99
 
 #ifdef __cplusplus
 #define __BEGIN_DECLS extern "C" {