Rename the asm-comments compiler flag to verbose-asm

Since this codegen flag now only controls LLVM-generated comments rather than
all assembly comments, make the name more accurate (and also match Clang).

compiler/rustc_session/src/options.rs

@@ -1630,8 +1630,6 @@ options! {
         "only allow the listed language features to be enabled in code (comma separated)"),
     always_encode_mir: bool = (false, parse_bool, [TRACKED],
         "encode MIR of all functions into the crate metadata (default: no)"),
-    asm_comments: bool = (false, parse_bool, [TRACKED],
-        "generate comments into the assembly (may change behavior) (default: no)"),
     assert_incr_state: Option<String> = (None, parse_opt_string, [UNTRACKED],
         "assert that the incremental cache is in given state: \
          either `loaded` or `not-loaded`."),
@@ -2107,6 +2105,8 @@ written to standard error output)"),
         "Generate sync unwind tables instead of async unwind tables (default: no)"),
     validate_mir: bool = (false, parse_bool, [UNTRACKED],
         "validate MIR after each transformation"),
+    verbose_asm: bool = (false, parse_bool, [TRACKED],
+        "add descriptive comments from LLVM to the assembly (may change behavior) (default: no)"),
     #[rustc_lint_opt_deny_field_access("use `Session::verbose_internals` instead of this field")]
     verbose_internals: bool = (false, parse_bool, [TRACKED_NO_CRATE_HASH],
         "in general, enable more debug printouts (default: no)"),