Switch to use pkg-config to find gnutls

configure.in

@@ -23,6 +23,7 @@ AC_SUBST(LIBVIRT_VERSION_NUMBER)
 
 dnl Required minimum versions of all libs we depend on
 LIBXML_REQUIRED="2.5.0"
+GNUTLS_REQUIRED="1.2.0"
 AVAHI_REQUIRED="0.6.0"
 
 dnl Checks for programs.
@@ -292,20 +293,38 @@ CFLAGS="$old_cflags"
 LDFLAGS="$old_ldflags"
 
 dnl GnuTLS library
-AC_CHECK_HEADER([gnutls/gnutls.h],
+GNUTLS_CFLAGS=
+GNUTLS_LIBS=
+if test "x$PKG_CONFIG" != "x" ; then
+  PKG_CHECK_MODULES(GNUTLS, gnutls >= $GNUTLS_REQUIRED)
+else
+  AC_CHECK_HEADER([gnutls/gnutls.h],
        [],
        AC_MSG_ERROR([You must install the GnuTLS development package in order to compile libvirt]))
-AC_CHECK_LIB(gnutls, gnutls_handshake,
+  old_libs="$LIBS"
+  AC_CHECK_LIB(gnutls, gnutls_handshake,
        [],
        [AC_MSG_ERROR([You must install the GnuTLS library in order to compile and run libvirt])])
+  GNUTLS_LIBS=$LIBS
+  LIBS="$old_libs"
+fi
+
+AC_SUBST(GNUTLS_CFLAGS)
+AC_SUBST(GNUTLS_LIBS)
 
 dnl Old versions of GnuTLS uses types like 'gnutls_session' instead
 dnl of 'gnutls_session_t'.  Try to detect this type if defined so
 dnl that we can offer backwards compatibility.
+old_cflags="$CFLAGS"
+old_ldflags="$LDFLAGS"
+CFLAGS="$CFLAGS $GNUTLS_CFLAGS"
+LDFLAGS="$LDFLAGS $GNUTLS_LIBS"
 AC_CHECK_TYPE(gnutls_session,
 	AC_DEFINE(GNUTLS_1_0_COMPAT,[],
 		[enable GnuTLS 1.0 compatibility macros]),,
 	[#include <gnutls/gnutls.h>])
+CFLAGS="$old_cflags"
+LDFLAGS="$old_ldflags"
 
 
 dnl Avahi library
@@ -513,6 +532,7 @@ AC_MSG_NOTICE([])
 AC_MSG_NOTICE([Libraries])
 AC_MSG_NOTICE([])
 AC_MSG_NOTICE([  libxml: $LIBXML_CFLAGS $LIBXML_LIBS])
+AC_MSG_NOTICE([  gnutls: $GNUTLS_CFLAGS $GNUTLS_LIBS])
 if test "$with_avahi" = "yes" ; then
 AC_MSG_NOTICE([   avahi: $AVAHI_CFLAGS $AVAHI_LIBS])
 else