[FFmpeg-cvslog] build: avoid stdin stall with GNU AS probing.

[Clément Bœsch]

ffmpeg | branch: release/1.2 | Clément Bœsch <u at pkh.me> | Fri Nov  8 23:55:06 2013 +0100| [d04e78805aa41b43d371ce9cd9b4fd2bf3af2989] | committer: Carl Eugen Hoyos

build: avoid stdin stall with GNU AS probing.

a758c5e added probing for various tools, such as AS. Unfortunately, GNU
AS is reading stdin with -v, and thus configure is stalled with
configure arguments such as --as=as.

Fixes Ticket #1898.
(cherry picked from commit dbb41f93c16cbc65a899a75723c95da51c851cd5)

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d04e78805aa41b43d371ce9cd9b4fd2bf3af2989
---

 configure |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index 58469a9..db768ce 100755
--- a/configure
+++ b/configure
@@ -2636,7 +2636,9 @@ probe_cc(){
     unset _depflags _DEPCMD _DEPFLAGS
     _flags_filter=echo
 
-    if $_cc -v 2>&1 | grep -q '^gcc.*LLVM'; then
+    if $_cc --version 2>&1 | grep -q '^GNU assembler'; then
+        true # no-op to avoid reading stdin in following checks
+    elif $_cc -v 2>&1 | grep -q '^gcc.*LLVM'; then
         _type=llvm_gcc
         gcc_extra_ver=$(expr "$($_cc --version | head -n1)" : '.*\((.*)\)')
         _ident="llvm-gcc $($_cc -dumpversion) $gcc_extra_ver"