libgpg-error: build error on Solaris 9

[Tom G. Christensen]

Hello,

I was unable to build libgpg-error HEAD on Solaris 9:
libtool: link: gcc -g -O2 -Wall -Wpointer-arith -Wno-psabi 
-fvisibility=hidden -o .libs/gpg-error gpg_error-strsource-sym.o 
gpg_error-strerror-sym.o gpg_error-gpg-error.o  -L/usr/tgcware/lib 
./.libs/libgpg-error.so -lintl -R/tmp/libgpg-error/lib -R/usr/tgcware/lib
Undefined                       first referenced
  symbol                             in file
sched_yield                         ./.libs/libgpg-error.so
ld: fatal: Symbol referencing errors. No output written to .libs/gpg-error
collect2: error: ld returned 1 exit status
make[3]: *** [gpg-error] Error 1
make[3]: Leaving directory `/export/home/tgc/tmp/libgpg-error/src'

Configure detects that librt is needed:
...
checking for library containing sched_yield... -lrt
...

However the makefiles do not actually use the value of LIB_SCHED_YIELD 
for anything so -lrt is missing at link time.

-tgc