Clearify macro IS_PATH_VAR_SEP in path.c so it is clear this is a path

variable, not a directory path.

src/port/path.c

@@ -41,9 +41,9 @@
 #endif
 
 #ifndef WIN32
-#define IS_PATH_SEP(ch) ((ch) == ':')
+#define IS_PATH_VAR_SEP(ch) ((ch) == ':')
 #else
-#define IS_PATH_SEP(ch) ((ch) == ';')
+#define IS_PATH_VAR_SEP(ch) ((ch) == ';')
 #endif
 
 static void make_relative_path(char *ret_path, const char *target_path,
@@ -110,7 +110,7 @@ first_path_separator(const char *pathlist)
 
 	/* skip_drive is not needed */
 	for (p = pathlist; *p; p++)
-		if (IS_PATH_SEP(*p))
+		if (IS_PATH_VAR_SEP(*p))
 			return (char *) p;
 	return NULL;
 }