Update an old suggestion in the Autotools Basics guide.

Fixes bug #484104.
Add a reference to the Gentoo Developer Handbook.
Merge pull request #9 from TomWij/patch-1

Add a reference to the Gentoo Developer Handbook.
Add note about architectures that don't have a stable keyword.
Destabilizes architectures to be consistent with the tree
Merge pull request #10 from mrueg/master

Add changes for architectures w/o a stable tree due to the latest council decision
epatch: Reword "larger patches"

Make it mention the devspace instead of mirrors

Bug 483292
ChangeLog: Add note about missing ChangeLog files

Bug #464216
common-mistakes: add 'Masking unsupported/broken useflags' section

Bug #483388