[PATCH v1] configure: record sphinx output

[Olaf Hering]

If configure fails to run due to errors in the expected sphinx
environment no helpful message is recorded. Write all of the output to
config.log to assist with debugging.

Signed-off-by: Olaf Hering <address@hidden>
---
 configure | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/configure b/configure
index 12dbb0c76b..55086b0280 100755
--- a/configure
+++ b/configure
@@ -4908,7 +4908,7 @@ has_sphinx_build() {
     # sphinx-build doesn't exist at all or if it is too old.
     mkdir -p "$TMPDIR1/sphinx"
     touch "$TMPDIR1/sphinx/index.rst"
-    "$sphinx_build" -c "$source_path/docs" -b html "$TMPDIR1/sphinx" 
"$TMPDIR1/sphinx/out" >/dev/null 2>&1
+    "$sphinx_build" -c "$source_path/docs" -b html "$TMPDIR1/sphinx" 
"$TMPDIR1/sphinx/out" >> config.log 2>&1
 }
 
 # Check if tools are available to build documentation.