From: Jonathan Nieder <jrnieder@gmail.com>
Date: Tue, 16 Aug 2011 12:07:19 -0500
Subject: Build: Use AM_SILENT_RULES if requested

So now you can run "./configure --enable-silent-rules && make" to get
output like this:

|   CC     liblzma_la-common.lo
|   CC     liblzma_la-block_util.lo
|   CC     liblzma_la-easy_preset.lo
[...]

This makes it easier to see what file each batch of compiler warnings
is associated to.  Since on the other hand it makes errors harder to
reproduce by hand (you have to use "make V=1"), disable it by default.

The implementation uses m4_ifdef to avoid depending on an automake
version that implements AM_SILENT_RULES (1.11 or greater).
---
 configure.ac |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/configure.ac b/configure.ac
index 0941e8e3..f18f8959 100644
--- a/configure.ac
+++ b/configure.ac
@@ -455,6 +455,8 @@ AM_PROG_CC_C_O
 AM_PROG_AS
 AC_USE_SYSTEM_EXTENSIONS
 
+m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES])
+
 if test "x$enable_threads" = xyes; then
 	echo
 	echo "Threading support:"
-- 
1.7.10.2