[module.reach] Remove redundant module implementation unit declaration

Author: ChuanqiXu9

source/modules.tex

@@ -1048,7 +1048,6 @@
 \end{codeblocktu}
 
 \begin{codeblocktu}{Translation unit \#5}
-module X;
 import M;
 B b3;                           // error: no reachable definition of \tcode{struct B}
 void g() { f(); }               // error: no reachable definition of \tcode{struct B}
@@ -1069,7 +1068,6 @@
 \end{codeblocktu}
 
 \begin{codeblocktu}{Translation unit \#2}
-module B;
 import A;
 Y y;                // OK, definition of \tcode{X} is reachable
 X x;                // error: \tcode{X} not visible to unqualified lookup