xrdb 1.2.2

• gitlab CI: add a basic build test
• Build xz tarballs instead of bzip2
• gitlab CI: stop requiring Signed-off-by in commits
• Variable scope reduction as recommended by cppcheck
• Use C99 struct initialization
• Rename variable dup to avoid shadowing dup() function
• Fallback asprintf: don't truncate output that has a \0 in string
• configure: raise minimum autoconf requirement to 2.70
• xrdb 1.2.2