configure: add test for POSIX threads

Reviewed-by: Aaron Plattner <aplattner@nvidia.com>
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>

configure.ac

@@ -43,6 +43,14 @@ AC_CHECK_FUNC([dlopen], [],
         AC_CHECK_LIB([dl], [dlopen], DLOPEN_LIBS="-ldl"))
 AC_SUBST([DLOPEN_LIBS])
 
+# Look for POSIX threads
+AC_SEARCH_LIBS([pthread_once], [pthread pthreads c_r], [
+    AS_IF([test "$ac_cv_search_pthread_once" != "none required"], [
+        PTHREAD_LIBS="$ac_cv_search_pthread_once"
+    ])
+])
+AC_SUBST([PTHREAD_LIBS])
+
 # Check for Doxygen.
 AC_ARG_ENABLE(documentation, AS_HELP_STRING([--disable-documentation], [Disable Doxygen documentation (default: auto)]), [DOCS=$enableval], [DOCS=auto])
 if test "x$DOCS" != xno; then