fix invalid C in new trycppif tests in configure script
an empty program is not valid and would be reasonable grounds for the
compiler to give an error, which would break these tests.
diff --git a/configure b/configure
index 042c41b..b679986 100755
--- a/configure
+++ b/configure
@@ -56,7 +56,8 @@
trycppif () {
printf "checking preprocessor condition %s... " "$1"
-echo "#if $1" > "$tmpc"
+echo "typedef int x;" > "$tmpc"
+echo "#if $1" >> "$tmpc"
echo "#error yes" >> "$tmpc"
echo "#endif" >> "$tmpc"
if $CC $2 -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then