Revert "exec: search commands in the current directory first on OS/2"

This reverts commit 89d461dd83db48540668ffe1283dfaa0faf3432b.

To avoid the incompatibility with Unix shell scripts not expecting that
a current directory is searched first and the security problems, let a
user prepend "." to $PATH explicitly if needed.

    modified:   exec.c

exec.c

@@ -1315,12 +1315,6 @@ search_path(const char *name, const char *lpath,
 		goto search_path_err;
 	}
 
-#ifdef __OS2__
-	/* look in a current directory first (OS/2 style) */
-	if (search_access(name, mode) == 0)
-		goto search_path_ok;
-#endif
-
 	namelen = strlen(name) + 1;
 	Xinit(xs, xp, 128, ATEMP);