Backporting AC_PROG_CC_C99 macro for redhat.
Backporting AC_PROG_CC_C99 macro for redhat.

Metaswitch/memcached,owendCB/memcached,cloudrain21/memcached-1,cloudrain21/memcached-1,couchbase/memcached,zbase/memcached,abhinavdangeti/memcached,owendCB/memcached,cloudrain21/memcached-1,daverigby/memcached,daverigby/memcached,daverigby/kv_engine,zbase/memcached,abhinavdangeti/memcached,mrkwse/memcached,zbase/memcached,Metaswitch/memcached,abhinavdangeti/memcached,couchbase/memcached,abhinavdangeti/memcached,zbase/memcached,couchbase/memcached,Metaswitch/memcached,Metaswitch/memcached,mrkwse/memcached,abhinavdangeti/memcached,daverigby/memcached,mrkwse/memcached,daverigby/kv_engine,cloudrain21/memcached-1,jimwwalker/memcached,daverigby/kv_engine,jimwwalker/memcached,mrkwse/memcached,owendCB/memcached,Metaswitch/memcached,jimwwalker/memcached,daverigby/kv_engine,owendCB/memcached,couchbase/memcached,daverigby/memcached,zbase/memcached