fmt-debug option

Allows disabling `fmt::Debug` derive and debug formatting.

compiler/rustc_span/src/symbol.rs

@@ -535,6 +535,7 @@ symbols! {
         cfg_attr_multi,
         cfg_doctest,
         cfg_eval,
+        cfg_fmt_debug,
         cfg_hide,
         cfg_overflow_checks,
         cfg_panic,
@@ -894,6 +895,7 @@ symbols! {
         fmaf32,
         fmaf64,
         fmt,
+        fmt_debug,
         fmul_algebraic,
         fmul_fast,
         fn_align,
@@ -937,6 +939,7 @@ symbols! {
         fs_create_dir,
         fsub_algebraic,
         fsub_fast,
+        full,
         fundamental,
         fused_iterator,
         future,
@@ -1280,6 +1283,7 @@ symbols! {
         new_binary,
         new_const,
         new_debug,
+        new_debug_noop,
         new_display,
         new_lower_exp,
         new_lower_hex,
@@ -1714,6 +1718,7 @@ symbols! {
         semitransparent,
         sha512_sm_x86,
         shadow_call_stack,
+        shallow,
         shl,
         shl_assign,
         shorter_tail_lifetimes,