Enable a few extra warning options, including -Walloca because it's
error-prone. Enable -Wdeclaration-after-statement to enforce the code
style. Disable -Wunused-parameter and -Wmissing-field-initializers
because these are pointless and don't catch bugs.
Inspired from the Weston and wlroots options.
Signed-off-by: Simon Ser <contact@emersion.fr>
