configure: Do not use pthread_create to check for pthread

Certain instrumentation addons leads to a false positive in configure
and link failures at the end of the build phase.

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
dcadec: Add some logging before returning on error

Based on a patch by Michael Niedermayer.

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Merge commit 'f058f384a0d76bfd125f4738dceab7c890186432'

* commit 'f058f384a0d76bfd125f4738dceab7c890186432':
  configure: Do not use pthread_create to check for pthread

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  dcadec: Add some logging before returning on error

Conflicts:
	libavcodec/dcadec.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
version.sh: add a little usage comment

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
version.sh: add preprocessing guards

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
build: rename version.h to libavutil/ffversion.h

Also the libavutil/ffversion.h will be installed.

Rationale:
* Applications might want to know FFmpeg's version besides the individual
  libraries'.
* Avoids file name clash between FFmpeg's ./version.h and lib*/version.h when
  a library source file includes both and is compiled on an out-of-tree build.

Fixes #1769.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Makefile: remove version.h on distclean

Without this nothing will remove it even if it isnt generated in newer
versions anymore.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>