[babl] configure: do not link with pthread on Android.

[Jehan Pagès <jehanp src gnome org>]

commit c02af8275feb49e970e3e5651465b6e99d05a63e
Author: Jehan <jehan girinstud io>
Date:   Tue Jul 4 14:05:34 2017 +0200

    configure: do not link with pthread on Android.
    
    It turns out Bionic (Android C library) has its own implementation of
    pthread. With this minor change, babl is fully cross-compilable for
    Android.

 configure.ac |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 75c4c87..fd18e3c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -264,6 +264,12 @@ case "$target_or_host" in
     MATH_LIB=
     THREAD_LIB=
     ;;
+  *-*-android*)
+    os_win32=no
+    PATH_SEP=':'
+    DIR_SEP='/'
+    THREAD_LIB=
+    ;;
   *)
     os_win32=no
     PATH_SEP=':'