Backport useful code from fixes for bug 1447.

* configure.ac: Cehck for inet_ntop.
* m4/libcurl.m4: Provide a #define for the version of the curl
library.
--

We do not have keyserver helpers anymore but this fixes may come handy
eventually.

configure.ac

@@ -1303,7 +1303,7 @@ AC_FUNC_VPRINTF
 AC_FUNC_FORK
 AC_CHECK_FUNCS([strerror strlwr tcgetattr mmap canonicalize_file_name])
 AC_CHECK_FUNCS([strcasecmp strncasecmp ctermid times gmtime_r strtoull])
-AC_CHECK_FUNCS([unsetenv fcntl ftruncate canonicalize_file_name])
+AC_CHECK_FUNCS([unsetenv fcntl ftruncate inet_ntop canonicalize_file_name])
 AC_CHECK_FUNCS([gettimeofday getrusage getrlimit setrlimit clock_gettime])
 AC_CHECK_FUNCS([atexit raise getpagesize strftime nl_langinfo setlocale])
 AC_CHECK_FUNCS([waitpid wait4 sigaction sigprocmask pipe getaddrinfo])

m4/libcurl.m4

@@ -65,6 +65,10 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
      AC_PROG_AWK
 
      _libcurl_version_parse="eval $AWK '{split(\$NF,A,\".\"); X=256*256*A[[1]]+256*A[[2]]+A[[3]]; print X;}'"
+     # More recent versions of curl-config have a direct --vernum
+     # option, but we'd like this code to work with older versions as
+     # well, so just convert --version.
+     _libcurl_vernum_parse="eval $AWK '{printf \"0x%06X\",\$NF}'"
 
      _libcurl_try_link=yes
 
@@ -188,6 +192,11 @@ x=CURLOPT_VERBOSE;
            AC_SUBST(LIBCURL_CPPFLAGS)
            AC_SUBST(LIBCURL)
 
+           _libcurl_vernum=`echo $_libcurl_version | $_libcurl_vernum_parse`
+
+           AC_DEFINE_UNQUOTED(LIBCURL_VERNUM, $_libcurl_vernum,
+                  [The version of the libcurl library in packed hex form])
+
            for _libcurl_feature in $_libcurl_features ; do
 	      AC_DEFINE_UNQUOTED(AS_TR_CPP(libcurl_feature_$_libcurl_feature),[1])
 	      eval AS_TR_SH(libcurl_feature_$_libcurl_feature)=yes
@@ -228,6 +237,7 @@ x=CURLOPT_VERBOSE;
      unset _libcurl_protocol
      unset _libcurl_protocols
      unset _libcurl_version
+     unset _libcurl_vernum
      unset _libcurl_ldflags
   fi