* Convert from AC_TRY_RUN to AC_RUN_IFELSE.
* Excellent suggestion from Paul Hargrove: use AC_CHECK_FUNC to look
for a Linuxthreads-specific symbol when we're cross compiling to
see if threads will have different PIDs (because AC_CHECK_FUNC
works properly even when in cross-compiling environments).
Background: the old/Linuxthreads-based pthreads implementation used
the Linux clone() call to make threads, which effectively meant that
each thread had a different PID. The new NPTL pthreads implementation
does things better, meaning that threads have the same PID.
Open MPI no longer supports threads with different PIDs -- we ripped
out the supporting code for threads with different PIDs because we
don't have systems available to test this on anymore (anyone who still
has such a system can still use older versions of Open MPI). Hence,
configure needs to determine whether the target system will have the
same PID for threads or not -- even if we're cross-compiling. The
current test compiles and runs a multi-threaded app that checks PIDs
of different threads, but we clearly can't do that in a
cross-compiling environment. So use AC_CHECK_FUNC in cross-compiling
environments.
Simple, no?
This commit was SVN r24537.
bffa5c8f7e