configury: fix asm atomic detection

there is no need to look for an assembly file when BUILTIN_GCC is used

Fixes open-mpi#3032
Refs open-mpi#3036

Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>

(cherry picked from commit open-mpi/ompi@2f4013c)

config/opal_config_asm.m4

@@ -11,7 +11,7 @@ dnl Copyright (c) 2004-2005 The Regents of the University of California.
 dnl                         All rights reserved.
 dnl Copyright (c) 2008-2015 Cisco Systems, Inc.  All rights reserved.
 dnl Copyright (c) 2010      Oracle and/or its affiliates.  All rights reserved.
-dnl Copyright (c) 2015-2016 Research Organization for Information Science
+dnl Copyright (c) 2015-2017 Research Organization for Information Science
 dnl                         and Technology (RIST). All rights reserved.
 dnl $COPYRIGHT$
 dnl
@@ -1125,7 +1125,7 @@ AC_DEFUN([OPAL_ASM_FIND_FILE], [
     AC_REQUIRE([AC_PROG_GREP])
     AC_REQUIRE([AC_PROG_FGREP])
 
-if test "$opal_cv_asm_arch" != "WINDOWS" && test "$opal_cv_asm_builtin" != "BUILTIN_SYNC" && test "$opal_cv_asm_builtin" != "BUILTIN_OSX" ; then
+if test "$opal_cv_asm_arch" != "WINDOWS" && test "$opal_cv_asm_builtin" != "BUILTIN_SYNC" && test "$opal_cv_asm_builtin" != "BUILTIN_GCC" && test "$opal_cv_asm_builtin" != "BUILTIN_OSX" ; then
     # see if we have a pre-built one already
     AC_MSG_CHECKING([for pre-built assembly file])
     opal_cv_asm_file=""