Merge remote-tracking branch 'qatar/master'

* qatar/master:
  build: clean up library installation rules
  vf_drawtext: Remove some write-only variables.
  libgsm: Drop const qualifier to silence compiler warning.
  docs: Remove needless configure options
  docs: Don't recommend adding --enable-memalign-hack
  libvo-amrwbenc: Add braces to shut up gcc warning.
  adts: Fix PCE copying.

Conflicts:
	configure
	doc/general.texi
	subdir.mak

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