Add test directive //@ ignore-endian-little

We already have //@ ignore-endian-big, this does the same for
little endian.

Author: 1c3t3a

src/tools/compiletest/src/common.rs

@@ -459,6 +459,10 @@ impl Config {
         self.target_cfg().endian == Endian::Big
     }
 
+    pub fn is_little_endian(&self) -> bool {
+        self.target_cfg().endian == Endian::Little
+    }
+
     pub fn get_pointer_width(&self) -> u32 {
         *&self.target_cfg().pointer_width
     }

src/tools/compiletest/src/directive-list.rs

@@ -58,6 +58,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "ignore-elf",
     "ignore-emscripten",
     "ignore-endian-big",
+    "ignore-endian-little",
     "ignore-enzyme",
     "ignore-freebsd",
     "ignore-fuchsia",

src/tools/compiletest/src/header/cfg.rs

@@ -205,6 +205,11 @@ fn parse_cfg_name_directive<'a>(
         condition: config.is_big_endian(),
         message: "on big-endian targets",
     }
+    condition! {
+        name: "endian-little",
+        condition: config.is_little_endian(),
+        message: "on little-endian targets",
+    }
     condition! {
         name: format!("stage{}", config.stage).as_str(),
         allowed_names: &["stage0", "stage1", "stage2"],

src/tools/compiletest/src/header/tests.rs

@@ -689,6 +689,22 @@ fn is_big_endian() {
     }
 }
 
+#[test]
+fn is_little_endian() {
+    let endians = [
+        ("x86_64-unknown-linux-gnu", true),
+        ("bpfeb-unknown-none", false),
+        ("m68k-unknown-linux-gnu", false),
+        ("aarch64_be-unknown-linux-gnu", false),
+        ("powerpc64-unknown-linux-gnu", false),
+    ];
+    for (target, is_little) in endians {
+        let config = cfg().target(target).build();
+        assert_eq!(config.is_little_endian(), is_little, "{target} {is_little}");
+        assert_eq!(check_ignore(&config, "//@ ignore-endian-little"), is_little);
+    }
+}
+
 #[test]
 fn pointer_width() {
     let widths = [