Rust: fix qltest on macOS, and add CI cross-platform testing of it

Author: Paolo Tranquilli

rust/ql/integration-tests/qltest/failing_cargo_check/does_not_compile.rs

@@ -0,0 +1,5 @@
+fn foo() {
+    wat
+    is
+    this?
+}

rust/ql/integration-tests/qltest/failing_cargo_check/functions.ql

@@ -0,0 +1,5 @@
+import rust
+
+from Function f
+where exists(f.getLocation().getFile().getRelativePath())
+select f

rust/ql/integration-tests/qltest/failing_cargo_check/options

@@ -0,0 +1 @@
+qltest_cargo_check: true

rust/ql/integration-tests/qltest/lib/functions.expected

@@ -0,0 +1 @@
+| test.rs:1:1:1:11 | foo |

rust/ql/integration-tests/qltest/lib/functions.ql

@@ -0,0 +1,5 @@
+import rust
+
+from Function f
+where exists(f.getLocation().getFile().getRelativePath())
+select f

rust/ql/integration-tests/qltest/lib/test.rs

@@ -0,0 +1 @@
+fn foo() {}

rust/ql/integration-tests/qltest/main/functions.expected

@@ -0,0 +1,2 @@
+| main.rs:1:1:1:12 | main |
+| test.rs:1:1:1:11 | foo |

rust/ql/integration-tests/qltest/main/functions.ql

@@ -0,0 +1,5 @@
+import rust
+
+from Function f
+where exists(f.getLocation().getFile().getRelativePath())
+select f

rust/ql/integration-tests/qltest/main/main.rs

@@ -0,0 +1 @@
+fn main() {}

rust/ql/integration-tests/qltest/main/test.rs

@@ -0,0 +1 @@
+fn foo() {}