[gnome-keyring] Fix cross compilation

[Michael Biebl <mbiebl src gnome org>]

commit 9641cade4ebe175058d9d9bb385f72f74af4c611
Author: Helmut Grohne <helmut subdivi de>
Date:   Thu Mar 2 14:48:42 2017 +0100

    Fix cross compilation
    
    Consider $ac_tool_prefix when searching for pkg-config.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 9060929..c02936c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -46,7 +46,7 @@ AC_PROG_MAKE_SET
 AM_DISABLE_STATIC
 AM_PROG_LIBTOOL
 IT_PROG_INTLTOOL([0.35.0])
-AC_PATH_PROG(PKG_CONFIG, pkg-config, no)
+PKG_PROG_PKG_CONFIG
 
 AC_TYPE_PID_T
 AC_TYPE_SIGNAL