On AIX, _PATH_BSHELL is /usr/bin/bsh but we want to use /usr/bin/sh

(which is usually ksh).  This makes sudo's behavior when executing
a shell without the #! magic number match execvp() on AIX.

src/exec_common.c

@@ -155,7 +155,7 @@ sudo_execve(const char *path, char *const argv[], char *const envp[], bool noexe
 	nargv[0] = "sh";
 	nargv[1] = (char *)path;
 	memcpy(nargv + 2, argv + 1, argc * sizeof(char *));
-	execve(_PATH_BSHELL, nargv, envp);
+	execve(_PATH_SUDO_BSHELL, nargv, envp);
 	sudo_efree(nargv);
     }
     return -1;