only print output of configure, etc. if they fail

Author: Charlie Somerville

script/cibuild

@@ -4,9 +4,16 @@ if [ -z "$CORES" ]; then
   CORES=16
 fi
 
-git clean -f -x
-autoconf
-./configure --disable-install-doc --prefix=`pwd`/inst
+function Q {
+  if ! "$@" > /tmp/ruby_ci_log; then
+    cat /tmp/ruby_ci_log
+    exit 1
+  fi
+}
+
+Q git clean -f -x
+Q autoconf
+Q ./configure --disable-install-doc --prefix=`pwd`/inst
 make -j $CORES
 make install
 make TESTS="-j $CORES" test-all