compiler: -Werror=return-type hardening
compiler: -Werror=return-type hardening

Warn whenever a function is defined with a return type that defaults to
int. Also warn about any return statement with no return value in a
function whose return type is not void (falling off the end of the
function body is considered returning without a value).

For C only, warn about a return statement with an expression in a
function whose return type is void, unless the expression type is also
void. As a GNU extension, the latter case is accepted without a warning
unless -Wpedantic is used.

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@ubuntu.com>

hallyn/lxc,ss1h2a3tw/lxc,hallyn/lxc,ss1h2a3tw/lxc,ss1h2a3tw/lxc,hallyn/lxc