configure: try pthread_create without -lpthread

For libc variants without a spearate pthread lib (like bionic), try
using pthreads without the pthreads lib first and only if that fails try
the -lpthread linker flag.

Bug: http://curl.haxx.se/bug/view.cgi?id=1216
Reported by: Duncan

diff --git a/configure.ac b/configure.ac
index 08ddbc5..1a46fd9 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -3158,14 +3158,26 @@ if test "$want_thres" = "yes"; then
   AC_CHECK_HEADER(pthread.h,
     [ AC_DEFINE(HAVE_PTHREAD_H, 1, [if you have <pthread.h>])
       save_CFLAGS="$CFLAGS"
-      CFLAGS="$CFLAGS -pthread"
-      AC_CHECK_LIB(pthread, pthread_create,
-        [ AC_MSG_NOTICE([using POSIX threaded DNS lookup])
-          AC_DEFINE(USE_THREADS_POSIX, 1, [if you want POSIX threaded DNS lookup])
-          USE_THREADS_POSIX=1
-          curl_res_msg="threaded"
-        ],
-        [ CFLAGS="$save_CFLAGS"])
+
+      dnl first check for function without lib
+      AC_CHECK_FUNC(pthread_create, [USE_THREADS_POSIX=1] )
+
+      dnl if it wasn't found without lib, search for it in pthread lib
+      if test "$USE_THREADS_POSIX" != "1"
+      then
+        CFLAGS="$CFLAGS -pthread"
+        AC_CHECK_LIB(pthread, pthread_create,
+                     [USE_THREADS_POSIX=1],
+                     [ CFLAGS="$save_CFLAGS"])
+      fi
+
+      if test "x$USE_THREADS_POSIX" = "x1"
+      then
+        AC_DEFINE(USE_THREADS_POSIX, 1, [if you want POSIX threaded DNS lookup])
+        curl_res_msg="POSIX threaded"
+      fi
+
+
   ])
 fi