update leftover references from -Cembed-source to -Zembed-source

Author: Mrmaxmeier

compiler/rustc_session/messages.ftl

@@ -14,7 +14,7 @@ session_crate_name_empty = crate name must not be empty
 
 session_crate_name_invalid = crate names cannot start with a `-`, but `{$s}` has a leading hyphen
 
-session_embed_source_insufficient_dwarf_version = `-Cembed-source=y` requires at least `-Z dwarf-version=5` while sesssion uses version {$dwarf_version}
+session_embed_source_insufficient_dwarf_version = `-Zembed-source=y` requires at least `-Z dwarf-version=5` while sesssion uses version {$dwarf_version}
 
 session_expr_parentheses_needed = parentheses are required to parse this as an expression
 

src/doc/unstable-book/src/compiler-flags/embed-source.md

@@ -6,5 +6,5 @@ object debug info section. It takes one of the following values:
 * `y`, `yes`, `on` or `true`: put source code in debug info.
 * `n`, `no`, `off`, `false` or no value: omit source code from debug info (the default).
 
-`-C embed-source` requires DWARFv5 and is only supported with the LLVM backend.
+`-Z embed-source` requires DWARFv5 and is only supported with the LLVM backend.
 Use `-Z dwarf-version=5` to control the compiler's DWARF target version.