Rollup merge of #78875 - petrochenkov:cleantarg, r=Mark-Simulacrum

rustc_target: Further cleanup use of target options

Follow up to #77729.

Implements items 2 and 4 from the list in #77729 (comment).

The first commit collapses uses of `target.options.foo` into `target.foo`.

The second commit renames some target options to avoid tautology:
`target.target_endian` -> `target.endian`
`target.target_c_int_width` -> `target.c_int_width`
`target.target_os` -> `target.os`
`target.target_env` -> `target.env`
`target.target_vendor` -> `target.vendor`
`target.target_family` -> `target.os_family`
`target.target_mcount` -> `target.mcount`

r? `@Mark-Simulacrum`

Author: jonas-schievink

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -796,7 +796,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
 
     fn visit_expr(&mut self, expr: &'a Expr) {
         match &expr.kind {
-            ExprKind::LlvmInlineAsm(..) if !self.session.target.options.allow_asm => {
+            ExprKind::LlvmInlineAsm(..) if !self.session.target.allow_asm => {
                 struct_span_err!(
                     self.session,
                     expr.span,

compiler/rustc_builtin_macros/src/test_harness.rs

@@ -37,7 +37,7 @@ struct TestCtxt<'a> {
 pub fn inject(sess: &Session, resolver: &mut dyn ResolverExpand, krate: &mut ast::Crate) {
     let span_diagnostic = sess.diagnostic();
     let panic_strategy = sess.panic_strategy();
-    let platform_panic_strategy = sess.target.options.panic_strategy;
+    let platform_panic_strategy = sess.target.panic_strategy;
 
     // Check for #![reexport_test_harness_main = "some_name"] which gives the
     // main test function the name `some_name` without hygiene. This needs to be