Device/Port: Fix timeout error

In the Port::FullRead method, a potential endless loop could occur,
which was only interrupted by the supplied timeout value.
debian/rules: disable -fno-strict-aliasing

Our code aims to be aliasing-safe.  No need for this workaround.
.gitignore: ignore debian/xcsoar-doc
debian/rules: don't set CFLAGS

This is redundant and useless, as Makefile already sets this according
to the DEBUG setting.
debian/rules: remove the remaining CFLAGS declaration
debian/rules: add variable TARGET
debian/rules: append TARGET to TARGET_OUTPUT_DIR

Allow building multiple targets in one git clone.
debian/rules: parse "clang" from DEB_BUILD_OPTIONS
po: update Spanish translation
po: update Slovak translation
po: update Russian translation
po: update Croatian translation
po: update Danish translation
Merge branch 'v6.7.x'
po: update xcsoar.pot and *.po
Event/Notify: delete copy constructor instead of deriving from NonCopyable