Bump solana_rbpf to version v0.2.15 (#21289)

Bumps [solana_rbpf](https://github.com/solana-labs/rbpf) from 0.2.14 to 0.2.15.
- [Release notes](https://github.com/solana-labs/rbpf/releases)
- [Commits](https://github.com/solana-labs/rbpf/compare/v0.2.14...v0.2.15)

---
updated-dependencies:
- dependency-name: solana_rbpf
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

programs/bpf_loader/Cargo.toml

@@ -22,7 +22,7 @@ sha3 = "0.9.1"
 solana-measure = { path = "../../measure", version = "=1.8.11" }
 solana-runtime = { path = "../../runtime", version = "=1.8.11" }
 solana-sdk = { path = "../../sdk", version = "=1.8.11" }
-solana_rbpf = "=0.2.14"
+solana_rbpf = "=0.2.15"
 thiserror = "1.0"
 
 [dev-dependencies]