If GIMME_DEBUG >= 3 then make.bash -v

We already have logic to handle `GIMME_DEBUG` looking like a number and
capturing more output here; just use one number higher to ask
`make.bash` to be verbose.

Slightly repetitive, but cleaner and easier to understand than
conditional arrays or stuff which would affect shellcheck if we relied
upon empty unquoted args being dropped.

With this and without the #159 unset of `GO111MODULE`, invoking as
`GIMME_DEBUG=3 GO111MODULE=on gimme master` reveals all the `use of
internal package` complaints which show that building Go itself is
incompatible with having `GO111MODULE` set in environ.

gimme

@@ -327,8 +327,12 @@ _compile() {
 		export CC_FOR_TARGET="${GIMME_CC_FOR_TARGET}"
 
 		local make_log="${1}/make.${GOOS}.${GOARCH}.log"
-		if [[ "${GIMME_DEBUG}" -gt "1" ]]; then
-			./make.bash 2>&1 | tee "${make_log}" 1>&2 || return 1
+		if [[ "${GIMME_DEBUG}" -ge "2" ]]; then
+			if [[ "${GIMME_DEBUG}" -ge "3" ]]; then
+				./make.bash -v 2>&1 | tee "${make_log}" 1>&2 || return 1
+			else
+				./make.bash 2>&1 | tee "${make_log}" 1>&2 || return 1
+			fi
 		else
 			./make.bash &>"${make_log}" || return 1
 		fi