Instruction introspection: don't hardcode discriminators

Patch anchor to allow access to the generated discriminators.

anchor

@@ -1 +1 @@
-Subproject commit 442c00634e847af84672727dc00b45a2c8d0a956
+Subproject commit b52f23614601652a99ec6c27aec77bd327363b31

programs/mango-v4/src/instructions/flash_loan.rs

@@ -10,6 +10,7 @@ use crate::state::{
 use crate::util::checked_math as cm;
 use anchor_lang::prelude::*;
 use anchor_lang::solana_program::sysvar::instructions as tx_instructions;
+use anchor_lang::Discriminator;
 use anchor_spl::token::{self, Token, TokenAccount};
 use fixed::types::I80F48;
 
@@ -141,7 +142,7 @@ pub fn flash_loan_begin<'key, 'accounts, 'remaining, 'info>(
 
                 // must be the FlashLoanEnd instruction
                 require!(
-                    ix.data[0..8] == [178, 170, 2, 78, 240, 23, 190, 178],
+                    ix.data[0..8] == crate::instruction::FlashLoanEnd::discriminator(),
                     MangoError::SomeError
                 );
 

programs/mango-v4/src/instructions/token_update_index_and_rate.rs

@@ -8,6 +8,7 @@ use crate::{
     state::{oracle_price, Bank, Group, MintInfo},
 };
 use anchor_lang::solana_program::sysvar::instructions as tx_instructions;
+use anchor_lang::Discriminator;
 use checked_math as cm;
 use fixed::types::I80F48;
 
@@ -46,7 +47,8 @@ pub fn token_update_index_and_rate(ctx: Context<TokenUpdateIndexAndRate>) -> Res
             // 2. we want to forbid cpi, since ix we would like to blacklist could just be called from cpi
             require!(
                 ix.program_id == crate::id()
-                    && ix.data[0..8] == [131, 136, 194, 39, 11, 50, 10, 198], // token_update_index_and_rate
+                    && ix.data[0..8]
+                        == crate::instruction::TokenUpdateIndexAndRate::discriminator(),
                 MangoError::SomeError
             );