Explicitly mark main() as public in executables to avoid an HP-UX

ld warning.

src/sesh.c

@@ -45,6 +45,8 @@
 
 sudo_conv_t sudo_conv;  /* NULL in non-plugin */
 
+__dso_public int main(int argc, char *argv[], char *envp[]);
+
 /*
  * Cleanup hook for error()/errorx()
  */

src/sudo.c

@@ -147,6 +147,8 @@ static struct rlimit corelimit;
 static struct rlimit nproclimit;
 #endif
 
+__dso_public int main(int argc, char *argv[], char *envp[]);
+
 int
 main(int argc, char *argv[], char *envp[])
 {