configure.ac: fix broken nettle_cfb8_decrypt detection

Given the fixed version of the function will be part of Nettle 3.6,
use pkg-config --atleast-version instead of a manually comparison of
the Nettle version.

Fixes #974.

Signed-off-by: Daiki Ueno <ueno@gnu.org>

diff --git a/configure.ac b/configure.ac
index fb24986bb6f8c5b26a559bb538111ed966a3d8e9..b5781fc58f52fbb8fa8ff284e8a2e3857c7a5d70 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -602,9 +602,8 @@ LIBS=$save_LIBS
 
 # Check if nettle has CFB8 support
 if test -z "$ac_cv_func_nettle_cfb8_encrypt"; then
-       # nettle_cfb8_decrypt in nettle 3.5 is known to be broken
-       ver=`$PKG_CONFIG --modversion nettle`
-       if expr "$ver" : '^3\.5\b' >/dev/null; then
+       # nettle_cfb8_decrypt in nettle upto 3.6 is known to be broken
+       if ! $PKG_CONFIG --atleast-version=3.6 nettle; then
                ac_cv_func_nettle_cfb8_encrypt=no
        fi
 fi