configure: fix mktemp test and fallback function

diff --git a/configure b/configure
index 123de51..895b855 100755 (executable)
--- a/configure
+++ b/configure
@@ -1792,11 +1792,11 @@ HOSTEXESUF=$(exesuf $host_os)
 : ${TMPDIR:=$TMP}
 : ${TMPDIR:=/tmp}
 
-if ! check_cmd type mktemp; then
+if ! check_cmd mktemp -u; then
     # simple replacement for missing mktemp
     # NOT SAFE FOR GENERAL USE
     mktemp(){
-        echo "${2%XXX*}.${HOSTNAME}.${UID}.$$"
+        echo "${2%%XXX*}.${HOSTNAME}.${UID}.$$"
     }
 fi