Bugzilla Bug 30345

For whatever reason, mjpegtools on this system always uses '-mcpu=i686 
-march=i686'.  Wouldn't be that big of a deal except that this machine's processor is a 
VIA C3-1G, the bastard cousin of the K6.  For whatever reason, the configure script 
has also decided that cmov support should be enabled, which isn't in the C3-1G's 
instruction set (cmov is an optional instruction.) 
 
This causes a number of "unexplainable" mpeg2enc/etc. crashes. 

Reproducible: Always
Steps to Reproduce:
1.
2.
3.

I have also just seen this in the latest stable build (1.6.1.90-r1).

As far as i can see configure never actually checks for the precence of the
instruction but rather just checks if --disable-cmov was given and then
disables it. mpcu/march comes from checking if cmov is enable and if enable do
uname -m and then based on it set mpcu/march else set it to i586.

It should maybe have something like what is described in this gcc-maillinglist
message (http://gcc.gnu.org/ml/gcc-patches/2003-09/msg00217.html)

In that case, it should just be a matter of

grep -q cmov /proc/cpuinfo || myconf="$myconf --disable-cmov"

But maybe the whole flag generation part of the configuration should be removed and replaced with the user CFLAGS...

Applied this and version bumped. Please test, and reopen if not working.