erigon: fix SIGILL error due to missing CGO_CFLAGS

Currently Erigon binary fails to start on some systems with:
```
 > erigon --version
Caught SIGILL in blst_cgo_init, consult <blst>/bindinds/go/README.md.
```
The reason for that are missing `CGO_CFLAGS` that can be seen here:
https://github.com/ledgerwatch/erigon/blob/v2.53.2/Makefile#L26

For more information on this see this `bsc` issue:
https://github.com/bnb-chain/bsc/issues/1521

Signed-off-by: Jakub Sokołowski <jakub@status.im>

pkgs/applications/blockchains/erigon/default.nix

@@ -22,6 +22,11 @@ buildGoModule {
   #   cc1: error: '-Wformat-security' ignored without '-Wformat' [-Werror=format-security]
   hardeningDisable = [ "format" ];
 
+  # Fix error: 'Caught SIGILL in blst_cgo_init'
+  # https://github.com/bnb-chain/bsc/issues/1521
+  CGO_CFLAGS = "-O -D__BLST_PORTABLE__";
+  CGO_CFLAGS_ALLOW = "-O -D__BLST_PORTABLE__";
+
   subPackages = [
     "cmd/erigon"
     "cmd/evm"