Ye olde Apple mktemp

[Ralph Seichter <abbot@monksofcool.net>]

Another quirk that occurs during the configuration phase on older macOS
versions (when they were still called OS X, actually) in the MacPorts
build farm:

  Checking for GMime session key extraction support...
  usage: mktemp [-d] [-q] [-t prefix] [-u] template ...
         mktemp [-d] [-q] [-u] -t prefix
  No.

Hooray for that ancient mktemp binary. :-/ The following local patch
solves the issue for me:

diff --git a/configure b/configure
index 8b80f0e0..fa715946 100755
--- a/configure
+++ b/configure
@@ -529,7 +529,7 @@ int main () {
     return 0;
 }
 EOF
-    if ! TEMP_GPG=$(mktemp -d); then
+    if ! TEMP_GPG=$(mktemp -d -t /tmp); then
         printf 'No.\nCould not make tempdir for testing session-key support.\n'
         errors=$((errors + 1))
     elif ${CC} ${CFLAGS} ${gmime_cflags} _check_session_keys.c ${gmime_ldflags} -o _check_session_keys \

Alas, "mktemp -d -t /tmp" is incompatible with GNU coreutils' mktemp,
while "mktemp -d -p /tmp" is not understood by Apple's variant because
of the "-p". I don't know what syntax would be universally acceptable.

Is there a way to pass platform-dependent parameters to mktemp with the
current build mechanics?

-Ralph