main/vim: factor out $_luaver

so the lua version does not need to be repeated in multiple places

main/vim/APKBUILD

@@ -11,11 +11,12 @@ url="https://www.vim.org/"
 arch="all"
 license="Vim"
 options="!check"  # some tests are failing
+_luaver=5.4
 makedepends="
 	gtk+3.0-dev
 	libx11-dev
 	libxt-dev
-	lua5.4-dev
+	lua$_luaver-dev
 	ncurses-dev
 	perl-dev
 	python3-dev
@@ -217,7 +218,8 @@ prepare() {
 }
 
 _build() {
-	vi_cv_version_plain_lua=5.4 ./configure \
+	vi_cv_version_plain_lua=$_luaver \
+	./configure \
 		--build=$CBUILD \
 		--host=$CHOST \
 		--prefix=/usr \
@@ -229,7 +231,7 @@ _build() {
 		--disable-nls \
 		--enable-acl \
 		--enable-multibyte \
-		--with-lua-prefix=/usr/lua5.4 \
+		--with-lua-prefix=/usr/lua$_luaver \
 		--with-compiledby="Alpine Linux" \
 		"$@"
 	make