configure.ac: fix pthread checking

configure.ac

@@ -147,7 +147,7 @@ if test x"$enable_native_winthreads" = xyes
 then
     CPPFLAGS+=" -I$STARPU_SRC_DIR/include/pthread_win32 "
 fi
-AC_SEARCH_LIBS([pthread],[pthread_create],,AC_MSG_ERROR([pthread library unavailable]))
+AC_SEARCH_LIBS([pthread_create],[pthread],,AC_MSG_ERROR([pthread library unavailable]))
 
 AC_SEARCH_LIBS([sqrt],[m],,AC_MSG_ERROR([math library unavailable]))
 AC_HAVE_LIBRARY([ws2_32])