[PATCH] [testsuite] Pass -lpthread in libs

[Yao Qi <qiyaoltc@gmail.com>]

"libs" is the right flag to pass a library to a linker, instead of
additional_flags.  Without this patch, the test case can't be complied
by clang.

gdb compile failed, clang: warning: -lpthread: 'linker' input unused

gdb/testsuite:

2017-11-17  Yao Qi  <yao.qi@linaro.org>

	* gdb.base/info-os.exp: Pass -lpthread in libs.
	* gdb.multi/multi-attach.exp: Likewise.
---
 gdb/testsuite/gdb.base/info-os.exp       | 2 +-
 gdb/testsuite/gdb.multi/multi-attach.exp | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/gdb.base/info-os.exp b/gdb/testsuite/gdb.base/info-os.exp
index 574da26..b3109e1 100644
--- a/gdb/testsuite/gdb.base/info-os.exp
+++ b/gdb/testsuite/gdb.base/info-os.exp
@@ -28,7 +28,7 @@ if [gdb_skip_xml_test] then {
 }
 
 # Compile test program.
-if { [prepare_for_testing "failed to prepare" $testfile $srcfile {debug additional_flags=-lpthread}] } {
+if { [prepare_for_testing "failed to prepare" $testfile $srcfile {debug libs=-lpthread}] } {
     fail "cannot compile test program"
     return -1
 }
diff --git a/gdb/testsuite/gdb.multi/multi-attach.exp b/gdb/testsuite/gdb.multi/multi-attach.exp
index 9397f85..52acc91 100644
--- a/gdb/testsuite/gdb.multi/multi-attach.exp
+++ b/gdb/testsuite/gdb.multi/multi-attach.exp
@@ -23,7 +23,7 @@ if {![can_spawn_for_attach]} {
     return 0
 }
 
-if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug additional_flags=-lpthread}]} {
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug libs=-lpthread}]} {
     return -1
 }
 
-- 
1.9.1