chore(license): avoid sourcing PKGBUILD in check subcommand

We don't actually need any data from the package, except the pkgbase
which is exclusively used during logging. Simply grep the pkgbase name
and use the path during early code path issues.

Component: pkgctl license check

src/lib/license/check.sh

@@ -94,19 +94,19 @@ pkgctl_license_check() {
 		pushd "${path}" >/dev/null
 
 		if [[ ! -f PKGBUILD ]]; then
-			msg_error "${BOLD}${pkgbase}:${ALL_OFF} no PKGBUILD found"
+			msg_error "${BOLD}${path}:${ALL_OFF} no PKGBUILD found"
 			return 1
 		fi
 
-		# reset common PKGBUILD variables
-		unset pkgbase
-
-		# shellcheck source=contrib/makepkg/PKGBUILD.proto
-		if ! . ./PKGBUILD; then
-			msg_error "${BOLD}${pkgbase}:${ALL_OFF} failed to source PKGBUILD"
+		if [[ ! -f .SRCINFO ]]; then
+			msg_error "${BOLD}${path}:${ALL_OFF} no .SRCINFO found"
+			return 1
+		fi
+
+		if ! pkgbase=$(grep --max-count=1 --extended-regexp "pkgbase = (.+)" .SRCINFO | awk '{print $3}'); then
+			msg_error "${BOLD}${path}:${ALL_OFF} pkgbase not found in .SRCINFO"
 			return 1
 		fi
-		pkgbase=${pkgbase:-$pkgname}
 
 		if [[ ! -e LICENSE ]]; then
 			msg_error "${BOLD}${pkgbase}:${ALL_OFF} is missing the LICENSE file"