test-rwlock1 build error on Solaris

[Tom G. Christensen]

Hello,

Building a full gnulib snapshot on Solaris is currently failing for me.

The error looks like this on Solaris 9:
/usr/tgcware/gcc49/bin/gcc -std=gnu11  -g -O2  -L/usr/tgcware/lib 
-R/usr/tgcware/lib -o test-rwlock1 test-rwlock1.o ../gllib/libgnu.a 
-lpthread -lm   -lm     -lm    -lm  -lm  -l
m
Undefined                       first referenced
 symbol                             in file
sched_yield                         test-rwlock1.o
ld: fatal: Symbol referencing errors. No output written to test-rwlock1
collect2: error: ld returned 1 exit status
make[4]: *** [test-rwlock1] Error 1

It looks like just a missing @YIELD_LIB@ in modules/lock-tests.

-tgc