Bump bpf-tools to v1.20

- Fix C standard library to include only reentrant versions of functions
- Use a version of solana_rbpf with fixed relocations handling
- Add a test of using C standard library functions in on-chain program

sdk/bpf/scripts/install.sh

@@ -92,7 +92,7 @@ if [[ ! -e criterion-$version.md || ! -e criterion ]]; then
 fi
 
 # Install Rust-BPF
-version=v1.19
+version=v1.20
 if [[ ! -e bpf-tools-$version.md || ! -e bpf-tools ]]; then
   (
     set -e