improve zsh completion
compdb: check that inputs is not empty
Merge pull request #758 from mathstuf/dev/fix-compdb-abort

compdb: check that inputs is not empty
Merge pull request #756 from ronnychevalier/rc/zsh_completion

improve zsh completion
Allow paths with '{' '}' in depfiles
Merge pull request #761 from maximuska/proposed/depfile_parser_fixes

Allow paths with '{' '}' in depfiles