fix(reference/{cstdlib,cstdio}): "/* implementation-defined */ => implementation-defined"

#1470 (comment)

Author: akinomyoga

reference/cstdio/eof.md

@@ -3,7 +3,7 @@
 * macro[meta id-type]
 
 ```cpp
-#define EOF /* implementation-defined */
+#define EOF implementation-defined
 ```
 
 ## 概要

reference/cstdio/filename_max.md

@@ -3,7 +3,7 @@
 * macro[meta id-type]
 
 ```cpp
-#define FILENAME_MAX /* implementation-defined */
+#define FILENAME_MAX implementation-defined
 ```
 
 ## 概要

reference/cstdio/stderr.md

@@ -3,7 +3,7 @@
 * macro[meta id-type]
 
 ```cpp
-#define stderr /* implementation-defined */
+#define stderr implementation-defined
 ```
 
 ## 概要

reference/cstdio/stdin.md

@@ -3,7 +3,7 @@
 * macro[meta id-type]
 
 ```cpp
-#define stdin /* implementation-defined */
+#define stdin implementation-defined
 ```
 
 ## 概要

reference/cstdio/stdout.md

@@ -3,7 +3,7 @@
 * macro[meta id-type]
 
 ```cpp
-#define stdout /* implementation-defined */
+#define stdout implementation-defined
 ```
 
 ## 概要

reference/cstdlib/rand_max.md

@@ -3,7 +3,7 @@
 * macro[meta id-type]
 
 ```cpp
-#define RAND_MAX /*implementation-defined*/
+#define RAND_MAX implementation-defined
 ```
 
 ## 概要