test(fixtures): add Arch package fixtures and prove Lua cross-validation probe

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <[email protected]>

testdata/srcinfo/mytool/.SRCINFO

@@ -0,0 +1,10 @@
+pkgbase = mytool
+	pkgdesc = Example custom-build package
+	pkgver = 1.0
+	pkgrel = 1
+	url = https://example.org
+	arch = x86_64
+	depends = glibc
+	source = mytool-1.0.tar.gz
+	sha256sums = SKIP
+pkgname = mytool

testdata/srcinfo/mytool/PKGBUILD

@@ -0,0 +1,20 @@
+pkgname=mytool
+pkgver=1.0
+pkgrel=1
+pkgdesc="Example custom-build package"
+arch=(x86_64)
+url="https://example.org"
+depends=('glibc')
+source=("mytool-1.0.tar.gz")
+sha256sums=('SKIP')
+
+build() {
+  cd "$srcdir"
+  ./configure --prefix=/usr
+  make
+}
+
+package() {
+  cd "$srcdir"
+  make DESTDIR="$pkgdir" install
+}

testdata/srcinfo/split/PKGBUILD

@@ -0,0 +1,26 @@
+pkgbase=foobar
+pkgname=('foo' 'bar')
+pkgver=1.0
+pkgrel=1
+pkgdesc="Split package example"
+arch=(x86_64)
+url="https://example.org"
+depends=('glibc')
+source=("foobar-1.0.tar.gz")
+sha256sums=('SKIP')
+
+build() {
+  cd "$srcdir"
+  ./configure --prefix=/usr
+  make
+}
+
+package_foo() {
+  cd "$srcdir"
+  make DESTDIR="$pkgdir" install-foo
+}
+
+package_bar() {
+  cd "$srcdir"
+  make DESTDIR="$pkgdir" install-bar
+}

testdata/srcinfo/vcs/PKGBUILD

@@ -0,0 +1,24 @@
+pkgname=mygit
+pkgver=r1.abc
+pkgrel=1
+pkgdesc="VCS package example"
+arch=(x86_64)
+url="https://example.org"
+depends=('git')
+source=("git+https://example.org/repo.git")
+sha256sums=('SKIP')
+
+pkgver() {
+  cd "$srcdir/repo"
+  git describe --long --tags | sed 's/^v//;s/\([^-]*-g\)/r\1/;s/-/./g'
+}
+
+build() {
+  cd "$srcdir/repo"
+  make
+}
+
+package() {
+  cd "$srcdir/repo"
+  make DESTDIR="$pkgdir" install
+}